A lot of attention gets paid to the power play in NHL hockey. Even though most of the game is played at five-on-five, dissecting the power play takes up a lot of the oxygen in commentary. Chris Krieder led the NHL this year with 25 power play goals, so it certainly seems important just from that point of view.

If you cast your mind back to last October, you might remember we focussed a little on the crackdown on cross-checking in the NHL. The refs called a lot more penalties for a while, and then, as we watched the power-play opportunities number decline week by week, they stopped.

I wanted to revisit that issue, just to see how this season ended, but also to look at a strange quirk of the numbers. Power-play scoring requires opportunity and ability, so the total power play goals scored league-wide can rise or fall from changes in either or those factors.   If goal scoring goes up, it might be more power plays or it might be better power plays or both.

This is the league average goals scored on the power play since the 1930s (provided by Hockey-Reference).

Notice how the most recent peak is the post-lockout season of 2005-2006. The number of goals then declined until it levelled out pre-second-lockout. The scoring rate has now declined to below the amount that was common pre-lockout. That average has been at or very near .6 per game since 2012. What flattened out the scoring rate at a time when save % is falling and overall goal scoring is rising? Was it opportunity or ability? I think you know without a chart, but let’s be sure:

These both start in 1964, as that’s when this sort of data began to be kept. So, as expected by anyone who watches hockey, the ability of teams to score on the power play on average has risen since a nadir in 1997-98. The systems and skills used on the power play are now approaching the level from the mid-80s when the goalie was standing there like a lemon, hopelessly unable to stop anything. Patrick Roy put an end to that, and it’s taken 40 years for the skaters to catch up.

But meanwhile the opportunities have been in decline. That peak in 2005-2006 is the post-lockout crackdown — the real one, not the fakes we’ve had since — and ever since that season, fewer and fewer penalties are called.

The result is what is likely a coincidental equilibrium in the total number of goals scored. It might be due to referees calling fewer penalties as a psychological response to goals scored on earlier power plays, but that seems too simple an explanation for a complex set of individual decisions and team strengths.

Regardless, the result is that you can be better at the power play all you like, and it won’t get you anywhere. Or does it? That’s the league average, so the goal of a team is not to achieve the average, it’s to be the best in the league.

And here we have the 2021-2022 power-play goals scored by team (from Evolving Hockey):

There’s some very obvious correlation with playoff success here. You have to have a good power play in the playoffs because usually you have to be good at everything. So even if it feels less important these days, a top power play is still a necessary thing.

It’s hard to find clear reasons for that decline in regular season penalty calls, although some of it might actually be fewer infractions. But it is clear that if the NHL wants to increase goal scoring at a time when the power-play ability is rising, then calling more penalties creates a lot more goals. At the same time, sending the message to all the teams that obstruction in the crease won’t be tolerated, that hooking, holding etc. will be called scrupulously frees up the offensively gifted to score even more at five-on-five.

It’s a win-win. And it’s a mystery why the NHL resists it so hard.

But be careful for what you wish for because if power-play opportunities are declining because actual infractions are going down, and would go down even more eventually after more rigorous officiating, the downward trend will resume after any crackdown. The goal scoring will follow it.

When people (me) say that hockey is a five-on-five game, this is partly why. The more the rule book is called, the cleaner the players play and the more the game is played at five-on-five. So the real goal of every team should be to have a roster that wins at five-on-five with the power play a bit of frosting on the cake. Just don’t tell the Avalanche that.