Individual Power Play Units in 17-18
The losers (2:18) and winners (10:40) of the offseason (featuring Vancouver, Washington, Ottawa, Montreal, Edmonton, New York, Buffalo, Toronto, and St. Louis), an analysis of last year’s top power play units (15:28).
#KarlssonWatch is back (1:05), our picks for next year's breakout players (3:53): Andreas Johnsson (4:30), Casey Mittelstadt (5:15), Dylan Strome (5:45), Travis Konecny (8:19), Alex Galchenyuk (10:08), Ty Rattie (11:52), Jordan Eberle (12:52), more on Mittelstadt because we just can't resist (14:22), our excitement over the season starting (16:11), more power play analysis (17:20).
(You can listen to us discuss this topic in these two episodes.)
My interest in looking at power plays initially spawned from a comment on Biscuits, Dave Lozo and Sean McIndoe's podcast, about how it'd be more intuitive to express power play success in terms of time (e.g., this team scored every eight minutes on the PP) than simply success percentage. Success percentage, the standard measure that most hockey media uses to determine the value of a power play, doesn't take into account how long a team actually spent on the power play. Rate stats (e.g., points per 60) are often better than stats that depend on a variable opportunity denominator (e.g., points per game) since they level the playing field, so to speak, and looking at minutes per goal (or seconds per shot) is just a new way of interpreting the standard goals per 60.
This was fairly easy to calculate on a team level (shown above, 5-on-4 regular season play only from 2017-18), and then I went further to identify the top power play units, those who logged at least 20 minutes together and netted at least one goal. That ended up being the top 98 units, and you can see the details of each by looking at the interactive visualization (or see the bottom of this page).
The top 10 units, in terms of time on ice, are shown above, sorted by minutes per goal. Toronto’s first power play unit topped this list, which wasn’t particularly surprising as someone who watched a lot of that power play last year.
(Also of interest to note: all of the top units in 2017-18 used four forwards and one defenseman. In fact, of the top 98 units, fewer than 25 percent used the three forwards-two defensemen structure. Matt Cane has written extensively about the benefit of using 4F-1D over 3F-2D. In summary, it's true that those units tend to allow more shots, but they also generate more shots, and have a higher shooting percentage, which puts the differential in their favor. This seems normal now, but it was under 10 years ago that 4F-1D on the power play was relatively rare.)
Speaking of Matt Cane, my next aspect of power play analysis uses his Power Play Structure Index, which is a weighted average of how far each player tends to shoot from their average location. Please read his work to see the full explanation, but in summary, a lower structure index indicates that a power play operates with a tighter formation, in that each player tends to take shots from a specific location. He also found that it’s a repeatable skill and nearly as predictive of future goal scoring as shot generation. He looked at this metric on the team level and found that over the past few years, the Capitals have performed best on this metric (i.e., had the lowest structure index). I calculated this metric for the individual power play units (those with at least 75 shots), and you can see those data in the interactive visualization (or see the bottom of this page).. The top 10 are shown above, and it shouldn’t be surprising that the Capitals rank high on this list as well.
And thanks to provided shot locations, we can construct shot maps in order to visualize the structure index, like with Washington's top power play above. Carlson’s on the blue line, Oshie’s in front of the net, Backstrom and Kuznetsov are a little bit all over the place, and Ovechkin doesn’t stray far from the Ovechkin Spot™.
The same is true of Toronto's top power play unit. You can clearly see Reilly along the blue line, Marner and Bozak mostly on the sides, and Kadri and Van Riemsdyk in front of the net.
Now contrast those first two gifs with Carolina’s second power play unit, which had the highest (and therefore worst) structure index among the qualified units. There’s a little bit of structure, but as you can see from how spread out the shots are, it’s not nearly as clear-cut as the other two units.
(If the visualization isn't showing up below, refresh your page or click here.)