Hi everyone! I’m finally back home from RITSAC, which was so great! It was awesome to meet everyone and see what kinds of things people are working on. For those who didn’t get a chance to see my presentation (or those who did but maybe feel like rewatching it), I’ve uploaded a PDF of my slides and embedded the video from the conference below as well. If you press play, it should start where I start presenting, but if it doesn’t for some reason, drag the bar to about 2:15:00.
In the last post, we introduced and accounted for the penalty kill in our power play analysis. In this one, we’ll be doing the same, but for breakouts and zone entries. I’m going to go through BU’s most frequently used breakouts and then detail the neutral zone forechecks they faced while trying to get up ice. Once those definitions and examples are out of the way, I’ll get into the actual entry numbers. Not as much coding here until we get to entries where I’m just going to query my tracked data with SQL.
We’re going to be using some play diagrams in this post, so here is a key to what each movement/arrow means. If it’s hard to see exactly what each line is doing in the charts, clicking on them should make them bigger and easier to read. I already know how impressive my skating backwards line looks, don’t worry, you don’t have to tell me.
The biggest thing in examining breakouts is they don’t look exactly like this every time the power play regroups or breaks out of their own end. Sometimes they don’t want to come all the way back, so they just swing in the neutral zone or high dzone to try and collect themselves there, and sometimes they just don’t adhere to this exact formation. Maybe PlayerX came down the opposite side that he’s supposed to be on so by the time the defenseman is routing the puck, PlayerX isn’t quite in his textbook position. Maybe a forechecker was coming down to pressure and the PP had to move the puck faster than it had time to set things up. Whatever the case may be, keep that in mind while we talk about breakouts because even if I map out what they generally look like, that doesn’t mean it’s what happens each and every time.
PP1 will usually use one of two breakouts: Single Drop or Five Back. They’re similar in the defensive zone, but do differ once the players progress. You can probably guess where the difference is based on the name, but I’m going to show you both regardless! They did tend to heavily favor the Single Drop but utilized both at different points.
You’ll see why I said these two breakouts are similar, mostly because they both bring all five members back to the defensive zone before carrying on. For both breakouts, Charlie McAvoy (7, D) acted as the conduit, controlling the puck and distributing it.
In the Single Drop, McAvoy takes the puck out of the zone from the net area (usually behind, but sometimes not) and will carry it out with Jordan Greenway (18, F) on the left wing and Patrick Harper (21, F) on the right wing. Those two will stay pretty level with McAvoy, creating a line of three heading up ice. Clayton Keller (19, F) and Jakob Forsbacka Karlsson (23, F) act as the second level of power play, hanging back a little in the inside lanes to McAvoy’s flank on the left and right. McAvoy then has the option to drop back to either one of them or can proceed forward. I’ll show examples of both through some gifs. The goal of the drop pass is to force the PK back with the first wave of players and then, in dropping the puck back, they open up some space for a clean, controlled entry from the second wave.
Here’s a good example of the space the PP is trying to create for a controlled entry (we will talk more about this lower down). McAvoy takes the puck up the middle of the ice and drops it off for JFK, who then immediately passes it across the center lane for Keller to carry in. The entirety of BC’s penalty kill is already almost to the top of the circles by the time Keller brings it in. This kind of quick pass doesn’t happen every time, though, as we see in another example.
In this instance, we can see a dramatic drop pass from McAvoy with some puck carrying by Keller after, instead of just passing it off. Unlike BC above, Maine’s right side didn’t really bite on McAvoy’s drop and just held the blue line, refusing to give up that padding into the zone and forcing Keller to make a pass to Greenway to his left. Keller and Greenway do a good job here keeping that entry alive and actually getting a shot off from it in the process.
These gifs are good because they give you a good sense of how the drop pass can work and go awry. If a team gets the PK to move back, then they’ve accomplished their goal and should be able to enter the zone with relative ease before being pressured. However, if a PK is expecting it or recognizes it soon enough, they can stop themselves at the blue line and create a log jam, or find a way to make life more difficult for the PP.
PP1 typically went through with the drop pass while in this formation, but here are a couple instances where they had to readjust or had the luxury of readjusting.
This is one of the “had to readjust” breakouts where McAvoy starts heading toward the right side of the ice and has his path impeded by a penalty killer. In taking the time to go around the PK, Keller has reached the point where he’s not really a drop option and is instead just a free entry pass option. It works out fine since Maine’s other three penalty killers had been retreating into the zone and gave up that space for Keller to enter, but it does force that difference in play.
This last drop example is not a drop at all but is instead Charlie McAvoy realizing he is entirely capable of just taking the puck in himself and doing so. The breakout starts in a drop formation with Keller and JFK back behind, but McAvoy decides instead to just carry it around the first penalty killer and maintains possession for a controlled entry that results in a shot attempt as well.
In the Five Back, McAvoy will come out from behind the net or head up from his spot along the goal line and will either pass to one of four swinging players or opt to take the puck up the ice himself. It’s a pretty simple basis for a breakout, and PP1 generally maintains these lanes, but they don’t always stay quite so set, with some guys occasionally switching lanes mostly due to the flow of play.
We see all five players come back like the Single Drop, but instead of proceeding to a drop formation, McAvoy passes off to JFK on the right in the outside lane, who then sends an exit pass to Harper. Harper doesn’t record a controlled entry here, but does recover the dump-in and helps the Terriers get possession back.
This is just a messy situation that I wanted to show as an example because it fits what I was saying earlier about breakouts not looking identical each time, even if they mange to get semi-set up. BU has two Lowell forecheckers deep in their zone and Harper does a good job in managing to fend them off by quickly cutting back with the puck. They continue on their trajectory out of the zone and give the Terriers some time to collect themselves and get reoriented. Harper gives the puck to McAvoy below him and JFK swings back to try and create some semblance of a breakout. It’s not a Single Drop breakout, but I’m not sure it’s organized enough to be called a Five Back one either. It’s definitely closer to a Five Back though. I also made the gif this long because I wanted to show just how good Lowell’s PK is and how fast they got to that puck and sent it out of the zone. We’ve seen BU recover a dump-in above and you’ll see some below when you continue reading, but not here.
PP2 runs a Four Man/Four Back/Center-Lane Option/Chicago Slash (according to Steve Spott), whatever you want to call it, breakout. Basically you have four guys back, one of whom is in charge of the puck (Chad Krys, 5, D), and then one (usually a forward, here Kieffer Bellows, 9, F) up at the blue line trying to draw defenders to him and clear entry lanes for the players coming up the ice. Something interesting to note here is that, in a Four Man/Four Back/Center-Lane breakout, the single swing side is often reserved for a defenseman instead of a forward, but BU has Dante Fabbro (17, D) on that double swing side and Patrick Curry (11, F) on the single side. For a Chicago Slash, the forward is on the single side and the second defenseman is on the double side, so that might be what BU was imitating here.
Anyway, what usually happens (more gifs!) is Krys hits either Fabbro up that right wing side, or will get it to Bobo Carpenter (14, F) towards the middle of the ice. I have a pass going to Curry as well because even though it’s not really a commonly used option, it is there. If Krys goes with Carpenter, Bobo takes it up the middle and can either pass it off to the wings or carry it in himself. In this example below, even though it failed and ended up being offside, you can clearly see what the Terriers were trying to do.
Carpenter’s pass ends up hitting Curry in the skate, and though Carpenter almost salvages the entry, Bellows as the stretch man has already entered the zone and doesn’t cut back out until it’s too late.
I’m loath to just call this a Center-Lane Option/Chicago Slash breakout because, as I said before, there are instances where Krys will go to Fabbro instead of Carpenter in the middle. In those cases (seen below), Fabbro will take the puck up the wing and can either dump it, pass it, or carry it in. Here, Fabbro dumps it past one of the penalty killers and then gets behind him to actually help regain possession for his team.
Here’s just another example of the above breakout where Krys goes to Fabbro. Dante takes the puck up the wing and does carry it in but dumps it shortly after while being pressured by the PK for Curry to snag in the far corner.
Fabbro will also sometimes go wide to Curry for an entry pass instead, but does tend to dump it this way.
PK neutral zone forechecks
We established in the previous postthat while using these power play units—and in video I had access to—BU played six different opponents through seven games (Yale, Boston College, Maine, Merrimack, UMass Lowell, and UMass Amherst). Five of those teams (everyone but Yale) are part of Hockey East and all five of them used a 1-3 neutral zone forecheck. Only Yale differed in using a 1-1-2/Same-Side Press.
I based these forecheck maps on the ones in Hockey Plays and Strategies by Ryan Walter and Mike Johnston just so I could give a consistent view of what’s usually happening in these forechecks.
In a 1-1-2 forecheck, the first forward enters the power play team’s zone and tries to get the puck carrier to either take the puck over to one side or force them to pass it to one side. If F1 succeeds, the second forward also pressures that side of the ice where the puck is heading to try and get the puck carrier/pass receiver to make a quick decision or F2 will completely close in and forces the PP to do something they don’t want to (i.e., dump the puck in). Both defensemen are then available to retrieve loose pucks that have been thrown into the zone in a last-ditch effort.
Like I said, only Yale used this forecheck in the games I had access to, and there aren’t really any super clear looks at it in the video (camera angle, guys changing, etc.) so I don’t have a good gif for an example.
Here’s one of McAvoy just walking around the forwards though.
F1 doesn’t really influence which side of the ice McAvoy is taking the puck to and McAvoy also cuts back toward the middle after looking like he was gonna go up that right side. After that, F1 tries to close that gap and catch back up with him, but McAvoy protects the puck and, by then, F2 is too far to the right to really make a difference in his path toward the attacking zone. It’s only when McAvoy hits the blue line and has three guys closing in that he has to pass the puck off but is blocked by F2, who’s in a good (maybe fortuitous?) place for the backhand to bounce off of him and into the corner.
For the 1-3, the first forward will swing into the zone and, depending if the puck is loose or possession is questionable, might go in deep to aggressively pressure the power play. However, if the power play clearly has the puck with control, F1 will instead exit the zone while still playing the puck closely as it comes out of the zone and try to get the play over to one side. Meanwhile, the other forward and both defensemen skate backwards to clog up the neutral zone by keeping lanes occupied and holding down the blue line. Like we saw before, this should make it harder for teams to enter with control as there isn’t a lot of empty space for them or the puck to go, so they wind up dumping the puck in and giving up possession.
McAvoy comes out from behind the net and starts up ice with one forward in deep trying to keep up with him. As he exits the zone, that forward continues to pressure, but McAvoy has little trouble getting away from him and passes the puck off to Greenway on his left. Instead of continuing through the blue line where Maine’s three remaining penalty killers are waiting, he passes back to Keller and delays the entry so BU has space to enter with control.
This is from the same game, but it’s a look at the forecheck succeeding in what it sets out to do. Some of the reason behind this is because BU doesn’t really do a full reset for their breakout, thanks in part to F1 pressuring down low so Jake Oettinger in net has to get that puck out of there quickly. Maine also gets a little boost from one of their guys changing here so they get four back a bit faster than if F1 had stayed on the ice. The Terriers not being able to get set in their lanes sees Greenway, JFK, and McAvoy all clumped on that left side of the ice with two Maine PKers standing up at the blue line and forcing Greenway to dump the puck in order to continue. The Black Bears get to it first and clear the zone with ease.
Let’s look at an earlier example of a PP1 breakout but this time from the perspective of the forecheck.
F1 and F2 are both hanging out in the zone at the start of this gif, but F2 starts to back off when the puck gets moved while F1 is pressuring McAvoy to pass off to his right. JFK takes the puck out of the zone and dishes to Harper, who’s facing two penalty killers at the line and has no real other choice except to dump it in. The forecheck has accomplished what it wanted to, but Harper does get behind them and gets possession back for his team.
Here’s actually another kind of Five Back example, but JFK is in charge of the puck instead of McAvoy. F1 comes into the zone but doesn’t spend a whole lot of energy trying to influence play. He doesn’t come in very deep, and it looks like he’s trying to read where the play is going. JFK passes up to Greenway on the left wing, but the UMass PK maintains a good gap with him so he must dump the puck past him to enter the zone. A scrum ensues in the corner for the puck and BU does not gain control or set up before the Minutemen clear things out.
One more example, and another one from before, is PP1 facing Lowell’s 1-3 forecheck.
Lowell is very aggressive in all aspects of their penalty kill, so their forecheck is no exception. They use a 1-3 but will send two forwards deep if there isn’t clear possession. Now we’re looking at this example from the other side of the puck. Lowell has managed to pressure the Terriers in their own zone enough that they’re playing along their right side and, though they keep possession, F1 lingers on the other side of the ice to keep play off to the right. F2 gets back in line with the defensemen (he did go off on a change so it’s someone else in his role), and one of the D gets over to that right side of the blue line to pressure aggressively. He steps up and gets BU to dump the puck despite the Terriers making a controlled pass through the neutral zone and just over the blue line. With nowhere to go, though, they had to give up control and take their chances with retrieval, which they fail at here.
Let’s start off this section by running through some definitions. As I went through video and tracked, I looked at the following things:
Opponent: who BU is playing
Unit: PP1 or PP2
Period and time: for my own use, self-explanatory
Enterer: the player who entered the zone (for faceoff entries, Enterer = 0 because play started in the attacking zone), I don’t know if that’s a real word but I needed a column name.
Result: what kind of entry it was: faceoff, carry-in, entry pass, dump-in, failed entry
Control: whether BU entered the zone with control or not (Y for carry-ins and entry passes, N for dump-ins and failed entries)
Possession: whether BU had/gained possession while/after entering the zone (this is mostly used for dump-ins and faceoff entries to see if BU got the puck back)
Setup: whether BU got set up comfortably in PP formation in the zone after entry or if it got a shot off on the rush after the entry
Goal: whether BU scored a goal on that entry
EBE: stands for entry-breakoutentry and is just an indicator to filter through events that were just entries (faceoffs, neutral zone regroups, etc., marked as E) vs. events that included a breakout and an entry (i.e. it starts in the dzone and BU has to exit, marked as BE)
NZFC: neutral zone forecheck being run by opposition
DZPK: dzone PK formation being run by opposition
I’m mostly just going to use tables to show totals and then add some commentary to round things out, but I’ll try to make it as easy to read as possible.
The table columns should be fairly clear, but this is a breakdown of each player’s entry tendencies. Let’s look at Clayton Keller because he does a lot and I’ve talked about McAvoy a bunch already. Keller was responsible for 14 of BU’s zone entries. He carried the puck in nine times, passed it in three times, and dumped it in once. He never recorded a failed entry (an entry stopped at the blue line/an offside entry), and if you combine his controlled entries (carries and passes), they tally 12. That leaves one uncontrolled entry and one (not in this table) that was a dump and change. Keller and Greenway each have one fewer entry categorized than their total because they each dumped it in and changed once, but I didn’t include those here.
You’ll notice, like in a couple other charts and tables, that Bellows is missing. That’s because he was not once responsible for a zone entry. Being the stretch man for his unit’s breakout likely is the cause of this, since his role was more to open up the blue line for someone else to enter.
Using more context, we see that McAvoy, Keller, and JFK led the way in terms of raw entry numbers, which makes sense when we think about their unit. First of all, PP1 obviously gets more ice time than PP2, so it makes sense that PP1 players have the most entries. Second, we know that PP1’s breakout of choice is a Single Drop, which runs through McAvoy, Keller, and JFK. They’re the ones moving the puck at or around the blue line, and with McAvoy as the lead breakout man, it’s not so surprising that he’s orchestrated most of the unit’s entries.
Fabbro and Carpenter head PP2’s entry totals, which you probably could have guessed after reading the breakout section. Krys has a similar role to McAvoy to start, but he typically passes the puck off before leaving the dzone while McAvoy doesn’t pass until he’s at the center line. Because of this, Krys isn’t as responsible for getting the puck in the zone as much as he is getting it out of his own zone. Instead, he usually tasks Fabbro or Carpenter with the job.
By entry type and unit
Here’s just a general overview of how many times BU used each entry separated by unit, and then the total for both units is on the right. The Terriers carried the puck in and passed it in 24 times each and then dumped it in 17 times for 65 successful entries. When we combine the carries and passes, we can see that BU entered the zone with control 48 times, meaning 73.85% of their successful entries were controlled ones. The first three groupings only include successful entries, as failed ones are listed afterward. So where PP2 had nine successful carry-ins, if we include the failed ones, they had 13 total attempted carry-ins. And I want to distinguish here that when I say successful, I just mean they were able to get over the blue line. If we want to look at the truly valuable entries, we can break this down further.
Quick explainer on the table. This is for both units, and individual unit analyses are in tables below. We’re breaking down whether each entry type resulted in possession and if the entry led to BU setting up in the attacking zone. Y means yes, and N means no. For the controlled entries, they obviously had possession through the blue line so all of those will be Y in terms of possession. What we’re really looking at are dump-ins and faceoff entries because they don’t necessarily come with possession. For those, we’re looking at whether BU gained possession after them. Faceoffs especially, the Terriers don’t have to have won the faceoff for possession to be marked Y, they just have to have possessed the puck at some point during the ensuing zone time (i.e., if the PK wins the faceoff but turns the puck over and BU gets it back).
On the whole, BU regained possession after a dump-in ~70.59% of the time and got set up in formation after a dump-in at that clip as well. The Terriers got possession following a faceoff 75% of the time and got set up after a faceoff 66.67% of the time. That’s what these particular percentages mean here. We’re looking at those specific entry types and how often they got possession/got set up for just that entry. For example, let’s look at carry-ins.
BU carried the puck into the zone 24 times successfully (we’re only looking at successful entries here because failed entries aren’t going to result in possession or setting up in the zone). Of those 24 times, 24 of them resulted in possession because BU, well, had control and possession while entering. However, if we look at how often a carry-in gets set up afterward, the value is 18. This means that in 24 carry-ins, BU set up 18 out of 24 times, or 75% of the time. They failed to set up six times out of 24 times, which is 25% of the time.
If we want to get more specific, here are similar tables but for each power play unit. It probably doesn’t do us a whole lot of good to dissect and compare each unit’s tendencies given how small the sample is, and the percentages don’t differ too, too much. Just take everything in context and remember the difference in breakouts!
Something we can look at though is how often each unit used a certain entry type. Again, PP2 had fewer entries than PP1 so we can’t really make any definitive, absolute statements about the two power plays, but we can use what we know to understand why each one operated the way it did.
I’m excluding faceoff entries while calculating %total because, while we want to keep track of them, teams don’t make the same kind of conscious decision for a faceoff entry that they do for others. They’re not really influenced by the PK in the same way, and if they are shooting for a faceoff, they’ve already entered the zone a different way anyway so!
Like I said before, there are three types of entries I was looking at: carry-ins, entry passes, and dump-ins. I recorded each time each unit attempted a certain entry and whether they succeeded in completing it or not. The top three rows in each of the tables below show how many times each entry type was attempted and what percentage of each unit’s total entries that ended up being. PP1 had 53 entries that were not faceoff entries and PP2 had 26, so the %total for each unit is the count of each entry type divided by the total number of entries each unit attempted.
PP1 was split evenly on which controlled entry it preferred, while PP2 seemed to lean toward carrying the puck into the zone. PP1 also dumps the puck in a fair amount, though two of those were dump and changes so you could argue for them to be excluded, but it wouldn’t take the percentage down all that much (15/53 = 28.30% vs. 13/51 = 25.49%).
If you look below the top three rows, you can see how often each entry failed. The %total is still divided by 53 and 26 here so what those rows are telling us isn’t how often a carry-in failed, but rather what percentage of each unit’s total entries was a failed carry-in. PP1 tried to carry the puck in 19 times and succeeded all by four times. This means that 7.55% of all of PP1’s entries were failed carry-ins, NOT that 7.55% of PP1’s attempted carry-ins failed. If we wanted to look at that, it would look something like this:
And again, a successful entry just means it gets past the blue line and isn’t stopped by the penalty kill there. If you want to see whether BU got possession, look back up at those tables above.
Entries vs forechecks
Lastly, I wanted to take a look at how each entry did against the two different forechecks. Like above, the first three rows for each forecheck include failed entries and are just counting for total attempts. Also like above, faceoff entries are excluded while calculating percentage, and the entries after the big three are the percentage of total entries that ended up being a failed carry-in, a failed entry pass, etc.
It’s not super telling to looking at the 1-1-2 because it was only over the course of one game, but we do see that BU was able to enter the zone with control more often than not and didn’t actually dump the puck in outside of one dump and change.
For all the entries against the 1-3 forecheck, there isn’t a ton of spread across entry attempts. The Terriers tried carry-ins most often, then entry passes, then dump-ins. I’m happy to see that dump-ins are not BU’s entry of choice on the power play, but they did go to them when needed.
If we want to see another further breakdown of how each unit fared against each forecheck, we can look below. Some of these numbers should look familiar since only PP1 faced a 1-1-2 forecheck and PP2 only faced 1-3 forechecks. The biggest difference is how PP1 did against the 1-3, which isn’t really all that different from how they operate as a whole. They’re still split on their controlled entries, but seem to go to the dump-in a little more often in comparison with their cumulative totals.
This table is still looking at the frequency with which each unit tried a particular entry against each forecheck. The percentages are similar to the above charts that look like these ones.
And if you want to see how many times an entry succeeded or failed vs. a certain forecheck, these tables should tell you.
In case it’s not clear what this table means, look at PP1 1-3 carry-ins. Of 16 total carry-in attempts, BU succeeded in entering the zone in 13 of them (13/16 = 81.25%) and failed three times (3/16 = 18.75%). That means that, when trying to carry the puck into the zone against a 1-3 forecheck, PP1 is successful 81.25% of the time and fails 18.75% of the time. It doesn’t look like an entry failed significantly against a forecheck. Percentage-wise, carry-ins had more trouble against the 1-3 than an entry pass did, but we don’t want to put too much weight into that since the actual sample size numbers are quite small.
Thank you for reading if you got this far! Or even if you didn’t! This is going to be my last post about this project (for now) since I have to turn my attention to putting all of this into slides now for my RITSAC presentation, but I will be back!
So many thank yous to Ryan Stimson for all his help with providing me resources to make this project the best it can be, and another thank you for some specific help on this post in giving second opinions and helping ID penalty kills and forechecks when they weren’t super clear!
In the last post, we looked at individual pass maps for players as well as their /60 pass rates. Now, I’d like to zoom out a bit and try to visualize team and unit tendencies, specifically whether these tendencies changed based on what penalty kill the Terriers are facing. Or maybe not “change” necessarily, but I’d at least like to see whether they’re at the whim of the PK or if they just carry on about their business regardless of who/what they’re up against.
Let’s start off by establishing which teams BU faced and what penalty kill they ran in those games. I’m going to explain each penalty kill and provide an illustration for each so we’re all on the same page. I’ll map out both defensive zone formation as well as neutral zone forecheck, but the latter won’t be discussed at length until my next post when I talk about breakouts and entries.
BU played each team once except for Maine who they played twice in a home and home series one weekend. The PP1 and PP2 columns just indicate whether that unit faced the particular opponent. Against Yale, BU was using a different PP2 (Bobo Carpenter, Patrick Curry, Ryan Cloonan, Brandon Hickey, and Chad Krys) even though that game was the first iteration of this PP1. For the UML game, there was only one personnel swap for PP2 (Nick Roberto in for Kieffer Bellows), but the coaching staff switched up the formation as well to an Umbrella PP with Curry and Roberto in front of the net. And when playing Merrimack, the Warriors used a Wedge+1 against PP1 and a simple Box against PP2. I’m trying to look at two very specific power plays in this project, so I omitted tracking the events that took place with those PP2s out on the ice. Reminder that PP1 is usually a 1-3-1 power play while PP2 is a split power play.
It’s pretty convenient for me that apparently at least half of Hockey East uses a 1-3 NZ forecheck on the penalty kill. I’m going to wait til next post to get into forechecks, though, just because as I’m writing this I’m realizing how long it’s going to be just with penalty kill formations. So first, numbers!
These are two tables that just note the number of shots (top) and passes (bottom) the team as a whole and each unit recorded against each opponent. Again, again, again we are extrapolating a lot, especially when it comes to breaking these rates down further and further. In that sense, I wouldn’t necessarily take the rates themselves as gospel, but instead use them as kind of a guide to what’s going on.
For example, at the rate the Terriers were passing against UMass Amherst, which ran a Wedge+1 penalty kill (see below for explanation), it appears that PP2 was moving the puck around more. They have a higher passes/60 than PP1. If we think about that in context, a Wedge+1 has one penalty killer running around chasing the puck, and since PP2 is more spread out and has four people at the points and on the boards compared to PP1 which has three in those spots, that +1 is chasing more people over a greater distance, so if the puck is being moved faster, he won’t be as effective as a different kind of penalty kill might be.
Here’s a look at the tables just organized by penalty kill, not opponent. Basically everything is the same as the top two tables except Merrimack (vs. PP1) and UMass have been combined into just the ‘Wedge+1’ row and Merrimack (vs. PP2) gets its own Box row. After combining them, we can see that shot rates between the two power play units do not differ significantly against a Wedge+1 PK, but PP2 is still passing much more when facing a Wedge+1. And like I said last post, that doesn’t necessarily mean they’re better or worse. It just means they’re different power plays and they’re moving the puck around more than PP1.
The Box is typically a passive penalty kill formation that aims to keep passes and shots to the outside. Players will move toward the puck carrier to try and pressure but just from a distance. They won’t go too far out and so are not aggressively on top of the puck. In a Large Box, though, players will be more aggressive and try to attack the puck carrier to force turnovers or quick decisions. However, this can take some penalty killers out of position and open up the middle, which the Box, as a PK, tries to keep the power play out of.
Yale used a Large Box penalty kill against BU, though as I mentioned before only the first unit faced it. It looks something like this to begin and then as the puck is moved around, it shifts toward one side of the ice or another and players (usually the forwards) will go out to the boards and points to pressure. The defensemen will also pressure, but from what I’ve seen they’re not quite as aggressive.
To see how BU fared against this penalty kill, I’ve put together a shot chart, a pass map, a failed pass map, and two heat maps: one that shows where passes started and one that shows where passes ended up. I wasn’t sure how to put them together without making it a bit overwhelming to look at. Click the images to see a larger version of them. If you see passes on the PP1 map made by a PP2 player or vice versa throughout, it’s because the majority of personnel on the ice were of that unit, even if the player isn’t a regular there.
Failed passes are passes that either didn’t make it to their intended target for a number of reasons, or they left the zone entirely (while possibly missing their intended target). I think the legend is self-explanatory, but RIM means a pass that was rimmed around the boards like before, BLOCKED means the pass was blocked by a penalty killer, and INT means the pass was intercepted with control by a penalty killer. Another one you’ll see later is BAD which just means it was a bad pass that wasn’t able to be corralled or kept by the receiver.
So the Terriers actually got two shot attempts off in the slot despite this being a Box-based PK. However, the goal was off the rush so they weren’t really in formation yet.
The density plots/heatmaps whatever you want to call them below are just to illustrate the above pass map in a different way. I thought this might make it easier to see the shape of BU’s passes through a density plot instead of just having you guys try and figure out the densities with just your eyes.
It looks like all but two of BU’s passes originated from outside the home plate area, and only one of those was actually in the slot, so Yale did a pretty good job at keeping a lot of the action on the outside. For where the passes ended, again, most of them ended up on the perimeter of the attacking zone or at the very bottom of that home plate area. And if you check back up at the pass map itself, only two passes actually went through the slot and one that tried to was blocked.
Now I’m going a little out of order, but Merrimack used a simple Box PK against PP2 when facing them. This allowed them to just pass the puck around the outside a bunch and kept them mostly out of the middle of the ice.
So just to reiterate, look at how empty the middle of the ice is. Merrimack wasn’t using a Large Box, so they were not applying heavy pressure, just kind of shifting their tight box toward the puck when it was moved. This allowed PP2 to operate how they wanted, but didn’t necessarily give up anything dangerous as nothing crossed the slot and just one shot came from inside the home plate area.
Now the Controlled penalty kill is similar-ish to the Box penalty kill in the sense that it sometimes uses the Box formation. Specifically, the Controlled PK stays in a Diamond formation when the puck is up high (ex. at the points) and pressures the point and then shifts to a Box when the puck is low (ex. below the goal line) and maintains a Box-like pressure.
Boston College faced the Terriers with a Controlled penalty kill, and this is how BU did against it!
A handful of those Patrick Harper/Clayton Keller passes on the right side there make up a lot of PP1’s passes against BC, and that’s due in part to that Diamond pressure. When Keller had the puck, usually the player on top of that diamond would come closer to attack the puck and force Keller to make a decision, and when he’d move it to Harper, the right-side penalty killer would then come out to pressure him. And here too we see some behind the net passes that we didn’t see against Yale above.
For PP2, if we look at the tables from before, we can see that they were passing at a pretty high rate for the length of time they were on the ice, but all these passes were super high and only two even originated/were received below the faceoff dots. They were only on the ice for 1:09 against this penalty kill and their PP is set up in such a way that everyone except Patrick Curry is positioned higher than the dots, so that’s probably most of it, but I don’t know how many valuable chances you’re going to get keeping the puck that high. I don’t really love the split power play, so some of this might just be my bias against it!
Credit to BC for keeping the slot almost completely clean for passes and shots, only allowing one successful pass and shot attempt. If you look below at the failed passes chart, you’ll see that the Eagles thwarted two pass attempts that made their way into/through the slot. PP2 completed all their passes, which is why there’s no failed pass chart for them.
And here’s a look at the pass densities!
A 1-1-2 PK is initially set up similarly to a Wedge+1 (see explanation below), but instead of just sending one guy out to chase the puck, the 1-1-2 has two penalty killers move to pressure the carrier and two stay in the slot in kind of a vertical line. I added that second illustration to show, for example, what happens when the puck is up near the corner and how the penalty kill moves.
So Maine used this penalty kill in both games and against both units while playing BU. The first unit has a really full pass map as you can see, with a lot of concentration in that Harper/Keller area again. PP2 again kept most of their passes up high, but did manage to get some passes a bit lower this time. They even got a clean pass across the slot there.
The samples with more data are more fun also because you can see shapes in the shots! PP1 has way more presence in the slot compared to PP2 which, as usual, sticks to its perimeter shape with a couple shots from in close by Curry.
I really like these PP1 density plots because I think they give a nice view of the shape, which again is due to a larger sample size. PP2 you can see just how much goes through Dante Fabbro and Chad Krys.
A Wedge+1 power play is basically what it sounds like. There’s a wedge (triangle) of three players that guard the low slot/slot and front of the net while the one remaining player goes out and pressures the puck. Depending on where the puck is, players can rotate in and out of the triangle so someone closer to the action is pressuring.
Merrimack used this power play against PP1 and UMass Amherst used it against both units. Like the 1-1-2 pass maps, there was a fair amount of ice time available to track for this PK, so things are a bit more fleshed out.
Lots of good pass movement for the power play against this penalty kill. One thing I’m noticing is that there doesn’t seem to be a ton of change in the way the power play operates based on penalty kill. The general locations are largely the same. PP2 is going to run through the defensemen no matter what, and PP1 operates often in that high triangle, but doesn’t have too much trouble getting down low.
More than against other penalty kills, BU sent the puck out of the zone on its own six times (three for each unit). Other than that, PP2 only failed behind the net and PP1 had a few around the slot interrupted and a few off to the sides.
In terms of shots, PP1 had a bit less slot presence than against the 1-1-2. This could have to do with the tight triangle guarding the slot, but BU still got plenty of chances right in front of the net.
Where there was a stark absence of pass starts in the middle of the ice for the 1-1-2, there are a few passes that PP1 makes more toward the middle, and the reception areas are similar. For PP2, that concentration remains at the points, but there’s definitely some more going on lower down.
The only way I really know how to describe this penalty kill is to show it in a play that actually happened, so here it is below. It’s a very aggressive penalty kill that UMass Lowell used that overwhelms the puck carrier by sending three people out toward the puck at a time while one holds down the fort in front of the net. In the play below, two penalty killers are on Jakob Forsbacka Karlsson trying to retrieve the puck below the goal line while a third tries to take away the pass option to Keller behind him. JFK doesn’t have control of the puck in this situation and Lowell ends up gaining possession. I’ll post a quick gif of it under the illustration so you can see it in action.
This is typically how the PK looks. If the puck is along the boards, those two penalty killers will create that 2-on-1 (or 2-on-2 if another PP member comes in) while a third eliminates a pass. When the puck is high or just being rotated at the points, it looks similar to a Box or Diamond that shifts based on the play and has players move out to pressure.
This penalty kill was incredibly successful against the Terriers, giving up just six successful passes to PP1 in 2:40 of play (small sample I know but still!). They were the second best penalty kill in Hockey East that year (only BU was better) and ranked ninth in the country.
I want to take a closer look at this penalty kill in the next post when I look at entries because a large part of this was preventing the Terriers from comfortably setting up. If things aren’t settled or in control, the PK swarms over to try and force a turnover and subsequent clear. As a preview, in seven entry attempts against Lowell, BU only got set up twice. They entered with control in three of those attempts and didn’t get set up in any of them. It’s impressive!
But because it worked so well against the Terriers, these charts aren’t super fun or telling. It just shows how well this penalty kill did really. There’s not a whole lot to absorb here!
One thing I will say is that PP1 only had three failed passes, which seems to imply Lowell wasn’t even really letting them attempt to pass it. This is why I want to look more at this, so I can show exactly why this was happening.
That’s all for this one. Thank you for sticking with me if you got to the end here. I had no idea this would end up being this long! For my next post (and I think last of this project), I’m gonna look at breakouts and entries. That should be up within the next week!
It’s been a little while since my last post, but we are back with some different data to look at this week. After getting most of our shot data sifted through in previous posts, we can look a little bit at some other stuff I was tracking, starting with passes.
To begin, here are a couple basic count plots that should give an idea of who was distributing the puck most for BU’s power play units.
So it’s not really surprising that Keller is far and away BU’s most frequent passer, considering PP1 is basically a ‘1-3-1 and Keller can do whatever he wants’ type deal. He absolutely orchestrated and quarterbacked the first unit for the Terriers during this power play. With 71 passes, Keller has everyone beat as Harper, with the second most, only has 53.
Here are further breakdowns of pass totals by unit.
Now the issue with just looking at pass totals is obviously the second unit is going to have fewer overall passes since they were on the ice much less often and had less time and fewer opportunities to pass the puck. By factoring time on ice into the equation, we can see whether the pass rates were similar or vastly different between power play units, without relying just on counts.
Obviously we’re extrapolating a fair amount here, especially with the second unit, but this at least gives us a look at whether the raw pass rates are all that different between PP1 and PP2. For example, we saw Keller had a dominant lead in passes over anyone on either unit, but the rate at which he passed the puck (125.74passes/60min) wasn’t too different than Chad Krys (135.00/60) or Dante Fabbro (139.05/60) on the second unit. Again, we have to be kind of careful here with the comparisons since the second unit played less than half the time the first unit did, but with what I had, Krys and Fabbro were on pace to surpass Keller’s pass rates.
This isn’t to pass any judgment on talent or rank power play members. It’s just to show that while Keller obviously was the conduit for PP1, PP2 ran through both Krys and Fabbro.
We can also see in the above table that PP2, using this data, had a higher Passes/60 rate than the first unit. Still, keep in mind they played far less time so it’s not clear that this rate would be sustained if they played the same amount of time. And again, this isn’t to necessarily say the first unit was more efficient or worse at moving the puck than the second unit. It could just mean that the second unit’s formation forced them to move the puck more, the way they open up the penalty kill might rely more on passing, they might simply be more stationary than the mobile first unit, etc.
To look a little bit more at the value of these passes, I tracked which ones immediately led to shot attempts. These are known as Primary Shot Assists.
You’ll notice Kieffer Bellows is not in the graph above and that’s because of his 15 passes, none ever directly led to a shot attempt. Again Keller has pulled away from the pack here, doling out 15 more primary shot assists than anyone else on either unit. Krys’ 10 pale in comparison until we look again at rate statistics and not just raw count.
Just to explain the table below in case it’s unclear, every ‘SA’ refers to primary shot assists, not shot attempts. We are looking at passes only here. The columns are self-explanatory except I think maybe %SA might not be super easy to gauge necessarily. I basically just wanted to look at what percentage of a player’s passes ended up being primary shot assists. For example, you can see Krys, Carpenter, and Keller each had about a third of their passes go for primary shot assists while Harper, who’s second in total passes, only had seven of his (13%) contribute directly to a shot attempt.
It’s just a snapshot peek into what’s happening here but, again, when you add in /60 rates you see that Krys is operating around the same pace as Keller for this particular sample of data. The two are both expected to record 44 or 45 primary shot assists per 60 minutes though, as I said before, having less TOI for the second unit might mean things even out to less than the first unit over time. Or they could stay the same, I don’t know!
If you look at the table, you might notice that Patrick Curry, Jordan Greenway, and Jakob Forsbacka Karlsson each have SA/60 in the single digits. While it may seem unimpressive, if you factor in their respective roles, it makes sense. Curry and Greenway spend almost all of their time directly in front of the net tipping pucks or trying to convert rebounds. JFK usually acts as the bumper on PP1 in the middle of the slot for deflections or will just shoot the puck from that close as well. Their jobs aren’t really to set goals up the way guys farther out are, so even though they might have a decent number of passes to their names, those passes are more to move things around. Greenway especially spends a lot of time behind the net with someone pressuring him, so a bunch of his passes are likely just to relieve that pressure.
And something else I wanted to bring up again because it’s interesting to me is Harper. He has the second most passes on the team, but doesn’t set a lot of things up. If we look at his pass map, it’s a bit easier to see why. The purple dots are where the passes originated, and the line shows where it went! Shoutout to FC Python for their pass map tutorial that inspired these charts.
[EDIT: I have updated the pass maps so that a pass that was indirect (off the boards) or rimmed around the boards is now a dashed line. This is so you can still see where the pass began but now you know it didn’t follow that exact path to get to its destination]
The vast majority of Harper’s passes originate around the edge of that right circle and 27 of them are received by Keller. That’s half of his passes to one person, and if you remember that Keller patrols the center point/high slot, you can see that many of Harper’s passes go to that general vicinity. The two of them sometimes pass back and forth between one another, or Keller will go to the other wall where McAvoy is set up. For Keller, 25 of his passes went to Harper while 24 went to McAvoy. They spent a lot of time moving the puck around that high triangle.
But back to Harper! If we narrow this down to just his primary shot assists, we can see where those came from in comparison to his other passes.
Alright so one thing that jumps out at me is Harper’s primary shot assists are very long passes, not quite the little back and forths that he does with Keller on the right side, though four of these are still to Keller. Another is that five of his seven primary shot assists are cross-ice and very lateral.
I’m going to show everyone else’s pass maps and primary shot assists charts below so you can compare for yourself.
And for all the nice things I said about Krys, take a look at where these shot assists are coming from. Obviously he’s playing down by the point on a stationary power play so he’s not going to get too crazy, but this is where the difference is. If you scroll down to Keller’s pass maps, compare the locations of his passes and which parts of the ice they cross. Krys here has one pass that crosses the slot (or “Royal Road” if you want to call it that), while all the others don’t really broach any super dangerous areas of the ice. They’re all far away. In fact, the shots taken after Krys passes are, on average, 38.98 feet away from the goal compared to Keller passes that yield shots from about 28.88 feet out. I don’t know how this turned into a Clayton Keller/Chad Krys comparison post, but I’d like to see what Krys can do with a little more freedom on the power play. I haven’t looked at a lot of footage from this past year in depth, and I haven’t checked other PP formations from this year at length, so he could have very well had more free reign with the man advantage already, but still! I’m intrigued.
These two are together because Bellows doesn’t have any shot assists and Curry’s sole shot assist is that pass down from the right circle to the right point. Lots of lower to high passes for these guys.
Those PP2 dmen were really glued to that blue line weren’t they.
Take a look at those passes from below the goal line, wowee. If you watched Greenway play at BU this is wholly unsurprising since that’s where he spends a ton of time just refusing to be knocked off the puck, but it’s still so impressive to see on a chart here.
Like I mentioned under Krys’ charts, Keller has much more variability with his shot assists and sent the puck to lower and more dangerous areas with some more movement. And check out the center point in his overall pass map. Remember what I said about that area being rather bare for shot attempts? Now you can see why!
As I said earlier in this post, a lot of JFK’s passes here on the left are not often setting up goals but instead, like Greenway’s, are likely relieving pressure or trying to get the puck to a better area for someone to work with.
Last note before I kind of wrap this up here. After seeing everyone’s pass rates, for individual players as well as whole units, I was kind of curious whether one unit passed the puck more before a shot attempt than the other. I figured the second unit would pass more since they don’t move as much, but the averages are almost identical. For both units combined, there are, on average, ~2.78 passes before each shot attempt. The average for PP1 is 2.77 (130 passes for 47 shot attempts) while PP2 posted a clean 2.80 (70 passes for 25 shot attempts).
And I think I’m gonna cut this post here! My next post is going to be about pass locations based on penalty kill formation to see if there’s anything that changes shape when BU is playing against a certain PK. I was debating whether or not to include it in this one, but we’re at 1700 words already so I will save it for next time.
I wanted to start off by thanking Matt Barlowe for helping me with some Python questions I had to make my code cleaner and easier to manage to make these diagrams. Thank you, Matt!
This post will focus on the results of each shot and take a look at individual player shot outcomes. It will likely be the last (maybe second to last) post that’s solely just standard shot data. I think a lot of the charts here are pretty self-explanatory, so there won’t be too, too much reading here. I think things will get a little more interesting soon, so stick with me!
To start, here’s an overview of each shot attempt for both power play units from where they were taken and whether it resulted in a shot on goal, a goal, a blocked shot, or a missed shot.
It’s clearer in the count plot below, but 43 shot attempts hit the net (48 with goals) while 32 missed the goal, 20 were blocked, and five went for goals.
And for closer looks at where each shot outcome occurred, here are charts for the results.
Shots on goal
Shots on goal ranged from all over the ice and don’t seem limited really to any one spot. Obviously they’re more concentrated around the net and the slot, but there isn’t much of the ice where the Terriers didn’t hit the net.
Of the 31 power plays I looked at, BU converted on five of them for a 16.1% success rate, a bit below its season average of 19.4%. The goals they did score, though, were scored mostly on the perimeter of the home plate region, which, as an entire space, is where goals are generally easier to come by than other places on the ice. The Terriers never scored from the middle of the home plate area, but all but one of their goals do fall there.
It’s not all that surprising, but there aren’t any blocked shots lower than that lowest hash mark. It pretty much goes without saying, but the fewer bodies in between you and the goal, the less likely it is that a shot will be blocked. If the Terriers fired shots from below the hash marks, they either missed the cage cleanly, hit it, or scored.
Shots off target
I don’t have much to say about the missed shots. They can clearly come from anywhere. If you compare it to the shot on goal chart, it doesn’t look all that different so that’s all! A lot of the ones close to the net were deflections—not point-blank misses—which I might get into in a later post.
Individual shooter outcomes
Now for a more individual look at these shot attempt results. Here’s a basic view of each player’s shot outcomes, with the first five shooters being members of PP1 and the next five of PP2. Again, because of sample size, it’s not the most extensive data, but it’s interesting to see how distance from the net impacts each player’s distribution.
I also wanted to look at the results for each unit on its own, so I just made some other charts that narrow things down. They’re basically the same as above, just with fewer data points. The shape of each unit’s shot attempts should be familiar from prior posts, but these visualizations give a bit more information than past ones.
In the graph below, you can see that PP1 had 31 shots on goal (35 including goals), 21 missed shots, 11 blocked shots, and four goals. With some simple division, we can tell that PP1 had a shooting percentage of 11.4%, which is up less than 2% from their season’s 9.95% figure in all situations (122 goals on 1226 shots). That’s not really giving them a huge advantage when they’re on the power play. If we look back above and count the number of shots in the home plate area though (15 shots, 3 goals), we can see that BU’s shooting percentage (3/15 = 18.75%) did go up when it shot from that space on the ice.
For a further breakdown of this, we can revisit the initial shooter outcomes but just with PP1 this time. The count plot makes a reappearance, and so do the individual shot charts from previous posts. These ones, however, have shot attempt results factored in, so it’s easier to see how effective each player was in his role. As usual, click through for the full size.
Greenway and Harper lead the way here with eight shots on goal apiece, while JFK, Keller, and McAvoy each contributed six. That only adds up to 34 shots because for the back half of one power play, Curry was in Greenway’s spot in front of the net with the rest of PP1 and hit the net and missed. So the first unit is credited with his shot totals, but they’re recorded in his individual chart.
I have to say, I’m pretty impressed with McAvoy’s ability to get the puck to the net from that distance so consistently. For contrast, take a look at Fabbro’s chart in the second unit’s section and see how many shots he got through for comparison. To be fair, McAvoy typically shot from closer to the net (average shot attempt distance: 40.47 ft) than Fabbro did (average: 56.25 ft). By moving toward the middle of the ice, too, McAvoy shaved his shot distances down a few feet, whereas Fabbro stayed farther to the right.
For a better look at average shot distances, I have included this table for PP1 and another below for PP2. Values are all in feet.
And here is our look at the second power play unit, which had one goal (from the home plate area) on 13 shots on net. That’s good for a 7.7% shooting percentage, 2% below the season’s all situation mark, though it’s not really that telling since 13 shots on goal is a veeeeery small sample to look at.
Like before, here’s a general count plot for the second unit. PP2 had 12 shots on net (13 with the goal), 11 missed shots, nine blocked shots, and one goal.
For a closer look at each player’s contributions, another count plot!
And here we have individual shot charts for the second unit, detailing again just how stationary they were as a power play.
Something I just wanted to touch on here for the shot distance table (all values in feet again) is that there seems to be a bit less variance in distance for the second unit. Again, the sample size isn’t doing me any favors here, but each player generally stays in his spot on this unit to shoot while for the first unit, shots aren’t necessarily taken in a set position. For example, Bellows had shots on goal, blocked shots, and missed shots all within a bit more than a two foot radius. The defensemen clearly had their heels in the vicinity of the blue line at almost all times, which wasn’t the case for the first unit. Curry never got farther than eight feet away from the net for a shot attempt, compared to his counterpart Greenway who slid around and fired a few chances on the rush.
In the next posts, I hope to take a deeper look at the strategy behind both units to see what worked and what didn’t work for each one, whether it was the penalty killers, the breakout, the neutral zone forecheck, the entries, etc. Maybe the first unit struggled in some places the second unit excelled, or vice versa, or maybe that’s not the case at all. Either way, now that we’ve gone through most of shots, we can move on to some more complex data and sequences.
Now we’re going to start getting into some more specifics. I’m not gonna go too, too deep on this post because I think the visuals will largely speak for themselves, so this is mostly just an extension of the previous entry.
Here, we’ll look at individual shot attempts and, in a later post, the results of those shot attempts. To start, here’s a more detailed view of the preliminary diagrams from the introduction. I’m not in love with the color scheme right now, and I wasn’t sure if it’s easy enough to distinguish player by color alone, so I made the markers different shapes as well in case that gives people a better view of what’s going on. These are also static visuals right now, and I might be playing around with Tableau for them in the future so it’s easier for people to actually interact with.
In the first power play unit, you can see that, for the most part, each player has a certain area they’re supposed to navigate around. Jordan Greenway and Jakob Forsbacka Karlsson have more set positions on top of the crease and in the slot, respectively. Patrick Harper, Charlie McAvoy, and Clayton Keller though are more at liberty to slide around and fill each other’s positions when one or the other shifts to a different part of the ice. Keller basically went wherever he wanted and McAvoy, while usually remaining on the left side of the ice, did venture more toward the right if it was vacant. And even though Harper—usually stationed in the right circle—has rifled his share of shot attempts from both circles, he typically will remain just about level with the faceoff dots there. Individual charts are provided beneath the first diagram and can be enlarged by clicking through.
Like I said in the previous post, you probably could have guessed every single shot that second power play unit took, and with very few exceptions that is true looking at this more specific visualization. Patrick Curry just never left the very front of the net, while Chad Krys and Dante Fabbro constantly toed the blue line with little incentive to venture very far. It’s interesting to me, though, and it will become clearer when I post the passing diagrams, that most of Krys’ passes came from farther to the left, but he actually moved toward the center point for his three shot attempts (the fewest of any player, as you can see). And then Bobo Carpenter and Kieffer Bellows pretty much just stuck to their circles for wristers and one timers.
I probably should have mentioned this before since it also applies to PP1, but all four half wall/boards/whatever guys (McAvoy, Harper, Carpenter, Bellows) play on their off sides. For those who don’t know what that means or are unsure, it means you play on the opposite side of the ice from what your handedness is. Basically, McAvoy and Carpenter shoot righty, so they play on the left side of the ice, while Harper and Bellows shoot lefty, so they play on the right side of the ice. It’s a way to involve the one timer in the power play easily.
Same as before for individual charts: click through on the thumbnails and you should be able to see bigger versions of each.
McAvoy and Keller in the NHL 2017-18
I wanted to take the time to see whether McAvoy and Keller were used in similar power play roles their rookie seasons with the Boston Bruins and Arizona Coyotes, respectively, or whether it differed at all. I used Harry Shomer’s Hockey-Scraper for Python and scraped data from the 2017-18 season and then narrowed it down to just power play events for McAvoy and Keller. Below, you will be able to see side by side diagrams of their NHL PP shot attempts versus their BU ones.
Something I noticed this season for the B’s was that, while BU used McAvoy on his off side for one timers, the Bruins used him more on his strong side. During the playoffs, they even had him with his former BU defense partner Matt Grzelcyk, which obviously made me incandescently happy.
Throughout the season, the Bruins had McAvoy sometimes as the quarterback in a 1-3-1 power play and others as the right point man in a split power play, which is why his NHL shot attempts veer in that center/right direction. I’m not sure that he was ever consciously or consistently used on his off side the way he was in college.
Keller, on the other hand, doesn’t visibly have too much of a difference in pattern (which is partially because my sample size is limited) besides the fact that he spent way more time in the slot in the NHL than he did for the Terriers. From this, though, before even looking at video, we can see that Keller was given the opportunity to move much closer to the net than at BU where he really manned the center point distributing the puck.
This season in the NHL, he played all over the ice on the power play. The Coyotes’ man advantage seemed fluid in terms of who plays where, with guys filling in whenever someone stepped to a different part of the ice. I’m not going to sit here and pretend I watched every Arizona power play from this season, but I’ve watched a fair number and I’ve already seen a 1-3-1, a split, and an overload for Keller on separate occasions, and he’s been all over for each. Just from looking at the diagram itself, though, it appears that he spent more time in the middle of the ice and on the right side of the ice.
Next I have to finish tracking passes and dive into a passing post, but before I do that, I’m going to look at the outcomes and shot types of BU’s power play shots. I’m trying to make this digestible I know it’s probably not super fun to only get chunks at a time but that’s what we’re going to do!
College hockey is not often publicly tracked, so this project came about from a desire to do something different. During the 2016-17 season, I ripped a bunch of Boston University men’s hockey games from the site they were being streamed on at the time. I figured it could be useful to have the video and I could find something interesting to do with it. Initially, I wanted to track entire games and get a spreadsheet up and running of everyone’s individual stats, as well as team ones. Long story short, I didn’t have the time to devote to that, so I narrowed my interest down to the power play. My goal is simply to quantify, illustrate, and analyze the BU men’s hockey team’s top two power play units from the 2016-17 season. This post will mostly serve as an intro to this project as well as a first look at what I’ve been doing and will be doing.
I have defined the top two units as the two most frequently used groupings of players (in the same formation) in the games that I had access to. That boiled down to a top unit of Charlie McAvoy (7), Clayton Keller (19), Jordan Greenway (18), Jakob Forsbacka Karlsson (23), and Patrick Harper (21) [4F1D, 1-3-1/umbrella-ish something formation they kept moving around] and a secondary unit of Bobo Carpenter (14), Kieffer Bellows (9), Dante Fabbro (17), Chad Krys (5), and Patrick Curry (11) [3F2D, split formation].
For those unfamiliar with power play formations, that means the two groups typically looked something like this:
One limitation of this project is sample size. With 31 power plays to look at over seven games for PP1, and 16 to comb through over five games for PP2, it seemed like I’d have a decent number of shot attempts to work with, and that’s mostly true. What I have can give a nice glimpse into the power play and shooting tendencies, but no one player had more than 15 shot attempts over the course of these games, making some individual charts look bare and patternless. I would have more, but not every game had video available for the public, or it wasn’t available for free, so I took as much as I could get. It should be enough for a snapshot of what the Terriers’ “ideal” setup was before tweaking it in the last handful of games of the season. There’s no shortage of passes, though, so that post will have fuller visuals to look at.
Another limitation is that the majority of the games I could snag were BU home games. This is a bit concerning considering the Terriers were 13-3-2 at home versus 8-6-1 on the road, but after calculating home-road splits for the power play itself, I found that BU operated with a 21.3% success rate at home (16-75) and an 18.6% success rate on the road (13-70), which is not a statistically significant difference at the α = 0.05 significance level. So, on the season, BU didn’t fare significantly better in their own rink versus others, despite the bump in percentage. Overall, their season power play conversion rate sat at 19.4% (33-170).
When it came to actual tracking, Ryan Stimson gave me access to a tracking tool he’s used with the Rochester Institute of Technology’s hockey team in the past that had been built by an RIT grad student. It allows the user to click where shots and passes occurred and then gives x and y coordinates of those events as well as shot distance, pass distance, shot angle, and more. I’m so grateful to Ryan for this because without it, I was going to track everything by hand and somehow digitize it. This way it’s much easier to work with and manipulate in Python. The image of the rink was also part of this tracker, and I have incorporated it into my visuals because, to be honest with you, I don’t know the exact measurements enough to draw the rink in Python. I can do the blue line and two red lines, but the others are tougher to align.
Now, to the specifics of this post! Because of all the introductions I had to get out of the way here, I’m only going to look at a very basic overview of shot locations in this post. The next one will be more player-specific and will even incorporate some NHL data (you can probably guess for who).
I just used matplotlib for these with the x,y coordinates of the shot attempts. Nothing is specified here in terms of whether the shot hit the net, went in, missed, or was blocked, and nothing is specified in terms of shot type either. Again, this is just a very basic look to get things started.
PP1 and PP2 shot locations
The above scatterplot indicates where each shot attempt from both units was taken. There’s a clear net-front presence here, which you might have guessed earlier looking at the formation diagrams. With Greenway and Curry stationed at the top of the crease at almost all times (Greenway had more leeway with where he could set up), there was usually a body making things difficult for the opposing goaltender. Not a lot of shot concentration in the high slot, and it looks like that’s the only real hole in the inner part of the ice, which is interesting, but understandable for the second unit specifically. Krys and Fabbro rarely ventured far past the blue line, which will be clear when I post the passing plots. For the first unit, Keller operated as the quarterback and would usually pass the puck around from that spot rather than shoot, so it makes sense that that area is a bit sparse as well. That one little blue dot in the corner there is a Carpenter shot that was not captured by the broadcast, but I wanted to credit him with a shot so it’s hanging out there for now.
Here we get a better look at PP1 itself. It’s a little messy at first glance, and will likely still be a bit messy when I go and differentiate between players, but the general shape is there. The biggest thing with this power play was that, even though everyone had their set roles, the players (especially Keller) were not afraid to slide around to other parts of the ice. It sometimes makes it hard to tell exactly what shape they’re going for, but they usually return to their “places”.
This is just very clearly a mostly stationary power play. Again, not a huge sample size so it looks a little empty, but the individual clumps are very distinct and show literally zero slot presence. PP2 was given a formation and instructed to stick to it, so much so that you can probably guess every shot without me even identifying which belongs to who. My personal favorite is that little Carpenter clump in the left circle there.
Now that we’ve gotten the basic shapes and locations out of the way, it’s time to get more specific with the next post.