On the Blue Jackets' Struggling Power Play

Yesterday I made a short post on the Blue Jackets' low PDO, making the point that we should expect the Jackets to have a much better second half as their shooting and save percentages climb back towards the mean. In the comments, Rob Vollman brought to my attention this Hockey Prospectus article by Timo Seppa, which brings into question Columbus' Power Play production dropoff after the transition from Ken Hitchcock to Scott Arniel. Timo asserts that

Arniel's track record wasn't favorable, particularly when compared to that of former coach Ken Hitchcock. In many aspects, the Blue Jackets had taken steps backwards since his departure, and they'd done no better than tread water elsewhere.

One example is on the power play. Never a particular strength of the Jackets—you need star players to have a truly upper echelon man advantage—the production of several key contributors had taken a highly visible nosedive in a year-and-a-half under Arniel's watch:

In other words, the dropoff in scoring under Arniel signifies a dropoff in overall power play production since Hitchcock left. This is a fine assertion to make judging by what these numbers tell us on the surface, however, I actually believe the Blue Jackets were a better PP team under Howson than Hitchcock. Let's take a look at why with some numbers via Behind the Net and NHL.com:

Season	5v4 SF/60 (NHL Rank)	5v4 SH%
2007-2008	44.8 (24)	11.4
2008-2009	47.2 (25)	9.4
2009-2010	51.8 (12)	12.9
2010-2011	53.7 (8)	8.9
2011-2012	53.5 (6)	9.1

Timo only looks at '08-09 onward, but I decided to include '07-08 under Hitchcock since I don't have the ability to break down the '09-10 season with splits before & after Hitchcock was let go. Regardless, it is clear from these numbers that Columbus actually increased their shot rate on the PP under Arniel to levels that the Hitchcock-coached team were never able to reach.

How, then, could have Columbus actually posted better scoring results under Hitchcock? The answer is simple: shooting percentage. As Jared has pointed out, there is a tremendous amount of luck involved in shooting percentages, especially in small sample sizes. When you're looking at results on the power play, it is important to keep in mind that PP shots are going to represent about 1/4 (or less) of a team's total shots throughout the regular season, enough where luck is still going to be a major factor in scoring goals. The fact of the matter is this: the shots were going in under Hitchcock, and they weren't under Arniel. Regardless of whether Rick Nash was playing in front of the net or on the half-wall, the team was still unlucky to shoot at such low rates under Arniel, which resulted in lower point production for the team.

Though there were definite shortcomings in Arniel's system, e.g. going into an absolute shell when up by 1 or 2 goals, this is more evidence that he was yet again on the wrong side of luck.

Is the Power Play Its Own Beast?

To what extent are even-strength and power-play performance linked? If your team is an offensive juggernaut five-on-five, should you expect them to dominate with a man advantage?

One might say that hockey skills are hockey skills and whatever helps you score at even strength should carry over. Thinking more about it, though, there are lot of aspects of the game that are in one but not the other. If your team excels at the breakout, On the Forecheck or has a mean neutral-zone trap then that won't help you too much when the other team simply clears the puck and waits for you at the blue line.

In the analytical community, the most-cited metric for power-play quality is shooting rate. See the recent article that got me thinking about this by Derek Zona or the definitive article on the subject by Gabe Desjardins. Since I am using 5-on-4 shots for per 60, the most obvious stat for comparison is 5-on-5 shots for per 60. So the question at hand is how correlated are 5-on-5 and 5-on-4 shooting rates.

Using data from BTN, over the last four full seasons the correlation between shooting rates 5-on-5 and 5-on-4 is 0.4. Normally I would put out an R^2 interpretation, but for this relationship it isn't one driving the other but some hockey skills and tactics driving both. Here is a graph showing the relationship:

With a correlation of 0.4 one could say there is a relationship between the two, but it isn't particularly strong. Luck is obviously one factor. We tend to focus on shooting rates because that reduces the luck factor, but it is still present. That is particularly true for the power play due to reduced sample sizes.

Here is a chart showing the average difference between 5-on-4 shooting rate and the one predicted by the above regression formula for each team. You can think of this as how good they have been 5-on-4 compared to offensively 5-on-5.

Team	Difference
S.J	8.19
ANA	7.94
DET	6.21
MTL	3.93
WSH	3.57
VAN	3.41
N.J	3.31
MIN	2.04
T.B	1.89
DAL	1.64
L.A	1.57
CBJ	-0.17
FLA	-0.22
BOS	-0.76
COL	-1.03
PIT	-1.09
BUF	-1.67
CGY	-1.75
NYR	-1.75
TOR	-1.9
PHI	-1.99
OTT	-2.44
STL	-2.45
NSH	-2.69
ATL	-2.76
NYI	-2.89
PHX	-3.62
CHI	-3.67
CAR	-4.25
EDM	-6.59

As you can see, the Sharks, Ducks and Red Wings are outliers at the positive end. Their power plays have performed better than you would expect based on their 5-on-5 shooting rates. The Sharks under McLellan have been very strong with the man advantage. The huge outlier in the graph above is the ungodly 72.6 5-on-4 shots/60 they put up last year. They currently lead the league this year at 68.8. Getting slightly off-topic, I think a safe prediction is for the Sharks to improve their power-play results since they top the league in 5-on-4 SF/60 but are only 10th in PP%.

On the bad end, the Edmonton Oilers stand alone. This is saying something, since the Oilers haven't exactly been machine gunning pucks at the net 5-on-5. Going by 5-on-4 shots for per 60 they have finished the last four years 30th, 30th, 30th and, you guessed it, 30th. This year Ryan Nugent-Hopkins can barely miss on the power play and perhaps he's helped their shooting rate out as well since they are currently all the way up to 24th in the league.

Given how consistently the Sharks, Ducks and Red Wings have outperformed expectations with the man advantage and how terrible the Oilers' power play has been, I think it's pretty clear that there is some skill component of the power play that is distinct from 5-on-5.

Power Play Trends: Why We Shouldn't Focus on Merely Results

As I was watching the CSN-Philadelphia broadcast of the Coyotes/Flyers game on November 18, during a break in the action of the Flyers’ first Power Play the following chart was shown to the viewer, entitled “Special Teams Reversal.”

	First 8 Games	Last 9 Games
Power Play	27.5%	9.3%
Penalty Kill	82.9%	90.2%

Presumably to reinforce play-by-play voice Jim Jackson’s comment at the beginning of the Flyers’ first man-advantage that the power play had been “struggling here of late,” I see a completely different trend when I look at the same numbers.

As Gabe Desjardins pointed out in this article, “The PP is all about directing shots on goal,” and I’m feeling daring enough to assert that the PK is all about preventing shots towards your own net. Looking at the Flyers’ shot rates per 60 minutes on special teams during the first 17 games once again thanks to JaredL, it becomes less surprising why such a reversal took place:

	First 8 Games	Last 9 Games
PP SF/60	50.7	40.7
PK SA/60	39.4	39.6

As of today, if the Flyers were to sport 50.7 SF/60 on the PP, they would rank 12th in the NHL according to BTN and 40.7 would put them 28th. Their PK numbers would rank them 2nd in both occurrences. What is more, if we look at the shooting data from the same span we see another trend bolder than Jaromir Jagr’s Movember ‘stache:

Power Play

	Shots	Goals	Shooting %
First 8 Games	53	11	20.8
Last 9 Games	46	4	8.7
Total	99	15	15.2

Penalty Kill

	Shots	Goals	Save %
First 8 Games	43	7	.837
Last 9 Games	44	5	.886
Total	87	12	.862

In addition to their more potent shot-generating PP in the first 8 games, the Flyers were shooting at an unsustainably high rate and opposing goalies were stopping an unsustainably low number of shots. The numbers are more reasonable on the PK, though the Flyers’ opponents were still running a bit warm with their shooting. As the sample size began to grow, we see the Flyers’ shooting percentage come back down to Earth as their opponents began to stop a more reasonable number of shots. Philadelphia’s PK numbers also even out by a bit less of a margin as we might expect based on the unit’s consistency.

Though such a turnaround may be alarming to those who still choose to judge power play success based on results, the fact of the matter is that the Flyers PP of the first 8 games was merely a mirage. As the season rumbles along, expect the Flyers’ special teams to mirror the second half of CSN’s chart rather than the first.