Outshooting Wins Games

David Staples, who writes the Cult of Hockey blog for the Edmonton Journal, and who has done a lot of interesting work during his time in the blogosphere (perhaps most notably breaking the Jaromir Jagr to Edmonton talks) is a guy I generally have a lot of time for.

Today, though, I must admit that his latest item drove me a little batty.

Staples compared two items from last season: a ranking of shots plus/minus and a ranking of goals plus/minus. He focused in on how many spots certain teams were out in the rankings, saw that some teams were a fair bit out (notably Boston, Vancouver and Florida) and while admitting that it’s possible he’s missing a flaw in his study, he concluded that good goaltending can throw the two items wildly out of whack.

Things I Don’t Like About the Staples Study

I do have a few issues with the way Staples conducted his little experiment, which I’ll explain now:

1. He focused on the edges rather than the pattern. There were really two ways of presenting this data: looking at the edges or looking at the average. Staples looked at the extreme outliers rather than focusing on whether – on average – the out-shooting team generally scored more goals.

2. He didn’t reference shooting percentage and save percentage. The obvious, and incredibly easy way to quantify the impact of goaltenders/shooters would be to include references to these; I suspect Staples’ looked at them because he talks about good and weak goaltenders, but he doesn’t give us any idea of how much better than average these goaltenders were.

3. He used only a single season. This I think is self-explanatory; the NHL has data going back years and running it back as far as the lockout would have been nice.

A Different Vantage Point

With regard to point one, I went to nhl.com and retrieved the goals +/- and shots +/- data. The chart below is goals +/- per game vs. shots +/- per game. The black line indicates the trend:

In short: the data actually suggests that out-shooting does help a team out-score as well, as evidenced by the trend line.

Finally, I knew that Tyler Dellow of mc79hockey.com had done some work on this topic before and that his findings more closely match the chart I did above, and sure enough he’d done a studyon how the post-lockout Oilers had fared in goals +/- vs. shots +/-. To quote his findings:

If you treat the ES portion of a hockey game as a separate game, which I think is the only sensible way to look at whether or not outshooting your opponent matters, the Oilers, since the 2005-06 season, are 36-42-33 when outshooting their opposition at ES, 31-63-27 when getting outshot and 5-5-4 when the ES shots tied. Just to be crystal clear, this is their record in the ES portion of the game – it seems foolish to me to look at the game as a whole when talking about ES outshooting. So, for example, if Edmonton outshoots their opposition 20-15 at ES and outscores them 2-1 at ES, but give up 3 PP goals and score none, I treat that as a win for the Oilers.

Finally, with regard to point four I again turn to Dellow’s work. He did a massive big-picture post on team’s records when out-shooting or getting out-shot; all of the data from 1987-2008 is included. The full study is here; for the sake of brevity I’ll just post the records:

  • Outshooting Team: 9451 W – 7116 L – 1979 T – 612 OTL
  • Outshot Team: 7728 W – 8647 L – 1979 T – 804 OTL

That strikes me as significant.

In short, yes teams can win while being outshot – shot quality game-to-game and goaltender ability certainly do factor in, but the fact of the matter is that the majority of the time the team taking more shots is going to win the game. And for all the talk of different strategies, shooter ability, goaltender ability and the like, the most important point is simply this: not once in the past twenty years have the out-shot teams posted better records than out-shooting teams.