Why the power play rules all in Stanley Cup Playoffs (Trending Topics)

As has been explored at length over the last few weeks, referees didn't exactly cover themselves in glory when it came to policing the various playoff series. The data suggests they called more penalties than in the regular season, but that certainly isn't enough for a lot of people, especially when so many games finished with so few goals. 

So far in these playoffs, 28 of the 47 games — almost 60 percent — featured five goals or fewer, and that includes empty-netters. That's poor enough scoring numbers that it would make the average NHL executive send out another email about maybe making the nets a little bigger. The 7-4 Game 6 between Calgary and Vancouver stands as the big outlier here; only 11 games of those 47 broke seven goals total. Often, those high-scoring games were not even wild affairs, but rather blowouts in which the losing team popped in a few meaningless punches to feel good about having suffered the onslaught.

So it would seem that the margins by which games are being decided are razor thin, and the difference between high- and low-scoring games is likewise not very big. People don't like to see hockey games end 3-2, because it's kind of depressing.

But that's the modern game, take it or leave it.

Which is what makes the cries for more penalties so important to note here. Because what people want when they say they want more penalties is more goals. In theory, teams would adapt to having so many calls go against them in the early goings and allow opponents to move unimpeded through the neutral zone and toward the goalmouth, and that in and of itself would create more goals. In theory.

The alternative to this is that if the “almost everything is a stick infraction” standard of 2005-06 were applied at the start of each season, the teams wouldn't need the learning curve come playoff time, and then we'd get free and easy hockey, plus more power plays. And that means more goals as well.

But those are pipe dreams for this season; as was stated earlier this week, to have refs start enforcing the rules far more strictly at this point in this playoff run would be impossible and unfair to all teams at the same time.

So instead we live in the system we live in.

But nonetheless, the small amount of power plays being awarded means that teams that can score on the power play are almost invincible, regardless of what they do in the much, much larger portions of the game played at 5-on-5.

The proportion of power play goals to those scored at even-strength is more or less unchanged from the regular season to the playoffs (ES goals made up 75 percent of all those scored in the regular season, compared with 76 percent through the end of the first round, while power plays came in at 22 percent and 21 percent, respectively).

But what's interesting is that because the number of goals being scored per game has dropped off — to 2.49 per team per game in the playoffs from 2.66 in the regular season — almost any power play goal is going to be worth more to the team that scores it in terms of affecting win expectancy. Call it a function of tight checking, conservative playoff hockey. But what's interesting is the correlation between being able to not necessarily scoring more goals, but simply draw more power plays per game than your opponents, and winning your series.

The three outliers here are the Islanders, Jets, and Predators. The through-line on why those teams didn't win their series is simple: They drew the penalties, and did not score on them, or conceded too many when they went to the box themselves. The Islanders didn't have a single power play goal, and lost in seven fairly tight games. Even one would likely have netted them a pass to the next round.

The Jets, meanwhile, the Jets had the third-worst penalty kill of any team in the playoffs (ahead of only Vancouver and St. Louis) 

Finally, the Predators were great on the power play and okay on the penalty kill; and though they lost in six games, those featured five overtime periods, and the Preds didn't score in them. The entire series is different if they do, obviously.

The problem in determining how important a goal, or any number of goals, is that hockey as a whole is random; 40 percent of results come from things that are outside the team's control — commonly referred to as luck, but this can define everything from a bad bounce to something like what happened to Ottawa in Game 6, getting a goal disallowed for no real reason. That skews things, and it's especially problematic in the postseason. Ottawa, it seems, did everything “right;” holding Montreal to a more or less even possession number, outscoring them dramatically in special teams, getting good goaltending, and so on. And they lost because Carey Price stopped 95.4 percent of the shots he saw at evens.

Individual games turn on power play opportunities. And because any one win in a series will significantly increase your chances of winning it, drawing as many penalties as possible is crucial. That's because the average number of shots you generate per minute goes up sharply, and so, consequently, does goalscoring.

On average, NHL teams saw an additional half a shot per minute when they were on the power play, and an extra 0.04 goals per minute as well. These may not sound like huge improvements, but they are. Shot generation more than doubled, and goals per minute increased 57 percent.

A lot of the goal and shooting percentage numbers you can chalk up to luck; teams generally cannot reliably drive their shot quality on the power play any more than they can at 5-on-5. But it's clear that it is much easier to score on the man advantage.

Teams that outscored their opponents on the power play alone went 18-7 in the first round (a .720 winning percentage). The vast majority of those games featured only one team scoring on the power play, and indeed, only five more featured teams tying with at least one power play goal each. The other 17 didn't feature any power play scoring at all.

That's why I'd give a lot of credence to people saying the Caps can and should beat the Rangers in their series. They had the best power play in the league in the regular season, and while even over 82 games a single goal can really skew a team's numbers (Detroit led the league with 70 power play goals on 294 chances, 57 more than what Washington got), that's why you have to draw as many penalties as possible.

To that end, Alex Ovechkin scores on the power play in Game 1.

Likewise, Calgary kept up its habit of not conceding too many man-advantage opportunities (they had the fewest against in the regular season) and consequently advanced in the first round.

Now these stats, or any others, used to potentially point definitively at a winner isn't going to hold up. That thing about how score-adjusted corsi-for in the previous 20 games picked 70-something percent of playoff series since 2005-06 correctly wasn't the case this year; that stat only nailed two of the eight series this time around. Should that rate go up in the second round? Probably. But at the same time, it might not. All you're doing is dealing in probabilities, and sometimes even a weighted coin comes up tails.

The playoffs are chaos. Still, you'd like to be able to hammer teams on special teams. It's important this time of year because there's just not a lot out there at 5-on-5.

Ryan Lambert is a Puck Daddy columnist. His email is here and his Twitter is here.