Princeton Hockey Corsi Primer

On Friday night, Princeton tied Yale 1-1 in the season opener.

Something coach Ron Fogarty has emphasized with Princeton is puck possession, so I’ve decided to track Corsi stats for the games this season (if the statistics are available).Corsi, the best way to calculate possession, is part of hockey’s “advanced” stats, although it’s not that advanced. The point behind Corsi is that you need the puck to score.

But stats don’t mean much without context, and it’s important to understand that possessing the puck doesn’t necessarily mean you’re getting quality scoring chances.

With Corsi you, must also take into account score effects. Supposedly, Corsi means more when the score is either tied or within a goal, because trailing teams will attack more.

Corsi is usually expressed in percentages (that’s how I use them.) The formula is Corsi For/Corsi Total. Corsi For is the number of total shots attempted (including shots that are wide or blocked) for one team, and total Corsi is the number of shots attempted total.

To help provide an idea of quality scoring chances against shots from the perimeter, I have pictures of the shot charts below.

Here are Princeton’s Corsi stats from last night’s game against Yale (note: I tallied the attempts based on the play-by-play, not on the shot charts):

First period:

5-on-5: 62.79 percent; total: 55.56 percent.

Shot chart First

Second Period:

5-on-5: 34.55 percent; total: 31.34 percent

Yale attempted 46 shots in the period, and seven came on a 5-on-3 power play. But the Tigers kept most of the shots to the perimeter.

Shot chart second

Third Period:

5-on-5: 52.38 percent; total: 52.78 percent

Shot chart third

Overtime:

5-on-5: 29.41 percent; total: 29.41 percent

Shot chart OT

Game Total:

5-on-5: 45.59 percent; total: 42.77 percent

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