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The Slow, Steady Decline of the Caps Power Play

The Caps power play unit is off to a terrible start to the season. How surprising is that, exactly?

NHL: JAN 13 Hurricanes at Capitals Photo by Randy Litzinger/Icon Sportswire via Getty Images

On Sunday evening in an eventual 3-2 loss to the Los Angeles Kings, the Washington Capitals received 6 power play opportunities and spent 12 full minutes with the man advantage, which are both highwater marks for the season. It doesn’t take a brain genius to reverse engineer that information to the realization that it means the team went 0-6 on those opportunities. In fact, they yielded a shorthanded goal, which was ultimately the difference in the game.

It was only the latest chapter in what’s been a frustrating year for the Capitals power play, which has been a sore spot on a season that’s otherwise been a lesson in grit and overcoming adversity. So far on the campaign, the Caps are only converting 15.6% of their chances, which makes it the fifth-worst power play unit in the NHL. This is in significant defiance of expectations; since 2013, only the Boston Bruins have had a more effective power play unit than the Caps, who have converted 22.3% of their opportunities.

What’s the significance of the start of the 2013? Glad you asked. That’s when Adam Oates handed the keys to the power play to Blaine Forsythe...apparently to the former’s surprise. From that 2013 article:

So, with that in mind, let’s have a look at the Caps’ power play journey over the course of the last eight-plus years. The following plot breaks down the Caps’ power play performance into 82-game, 41-game, and 20-game rolling average segments, chosen for their representations of full-season, half-season, and approximately quarter-season tranches.

What really jumps off the plot is where the 20-game and 41-game averages are currently printing. The Caps have seen a few 20-game stretches that are as bad as the current start to the season, but it’s been happening more frequently lately. This is about as bad a 41-game stretch as the Caps have ever had since Forsythe took the reins.

Let’s cut through the noise a little bit and examine the general trend of these moving averages.

We don’t need to look too closely at something like this. It affirms what Caps fans have probably observed over time from their couches - the power play’s effectiveness has been steadily declining for the better part of a decade. This view purposefully eliminates a lot of nuance - the power play unit has seen plenty of ups and downs during this period, but the overall trend is statistically down.

To hammer on the point even further, let’s look at that performance as a distribution of values instead of a time series. This just means that fattest part of the curve is where the power play has been most likely to perform since 2013. The dotted vertical line is illustrating where the unit is currently performing.

For the 20-game rolling segment, the current performance is far to the left of the distribution, which means it’s underperforming to a level that is very infrequent based on the last 8 years of data. Let’s have a look at the same view for the half-season and full-season based segments.

It’s much the same story no matter which time frame you’re looking at. The highest point of the distribution represents where the team performs most frequently, and in all three instances the current performance is undercutting that point by a very significant margin.

Let’s add another dimension back into this analysis: time. Although this time we are going to use the median performance of the Caps’ power play as a fulcrum for the analysis. On the below plots, stretches of time where the Caps were underperforming Forsythe’s median level of performance, the area is shaded red. Where they were overperforming, it is shaded green. Let’s start with our shortest time frame.

It is extreme disconcerting how much of the back half of this plot is shaded red. Not only are recent years more heavily shaded red, but the duration of those red periods is demonstrably longer than the periods of overperformance. Keeping this method for reading the chart in mind, let’s take a look at our 41-game moving average.

The longer time windows eliminate some of the noise and help highlight the key takeaway: that the Caps underperformance is nothing new. It’s been ongoing for several years, and as Blaine Forsythe’s tenure has gone on, his ability to course-correct his unit has diminished, and periods of overperformance against his own standard have decreased in duration.

This has very much been an analysis of the what more than the why, but ultimately Forsythe is responsible for both the inputs and the outputs. He’s certainly earned the right to a very long leash through the years, and we’d be remiss not to acknowledge the extenuating circumstances around the Caps’ current player availability, and especially in the skilled ranks.

That said, the evidence points to this poor performance being the continuation of an already established trend rather than symptoms specific to this season, and given how long that trend has been in effect, it’s more likely that Forsythe has more slack behind him than ahead of him.