Corsi Versus Reality: A Philadelphia Flyers Primer

One Man’s Season Long Journey Alongside the Advanced Metric of Corsi.

The game of hockey is a series of complex and grand paradoxes, beautiful and ugly, artistic and destructive, all compelling and contained on 200×85 foot sheet of ice.  Some things we see on that ice are amazing, some unbelievable, still others, mind boggling.  There are some we don’t at all understand, and some we don’t see at all, especially if you are an NHL referee.

For years the fans and fixtures alike have tried to capture this most complex and nuanced game with the use of statistics.  Goals, assists, points, penalties in minutes, goals against average, save percentage, wins, losses and ties have been counted to try to further our understanding of the game, and the teams and players that play them.

With the advent of the DVR the world of stats has hit something of a golden age in the NHL.  Naturalstattrick.com is practically Mecca for stat heads, they count just about everything that can be counted, and it will be the data source of this seasons research on corsi.

Corsi percentage has been hailed as the metric for “puck possession” by many and thought by some of it’s ardent supporters to be the bellwether metric for team and player success or value.

Others have pointed out the metrics short comings like shot quality and game situation.  Critics contend that with out the proper context the metric is far less useful than +/-.

Corsi percentage is at its core, a percentage representation of two counting statistics, team shot attempts for and team shot attempts against.  The formula is simple:

(shot attempts for)/(shot attempts for+ shot attempts against)

Typically, a percentage above 50% is considered to be good, for measure Tomas Tatar lead NHL regulars in 19-20 at 60.14%, whereas Brett Howden was last at 40.42%.  This example nicely depicts the historical variance between the two extremes. Does this mean that Tatar is the best player in the league and Howden the worst?  Just like hockey, the answer is not so simple.

As we examine corsi through out the season we will look at the story behind the numbers and test the validity of corsi’s use as an indicator or predictor of success.  We seek to examine if shot attempt differential tells an accurate story of a player, a game or a season.  Join us as we answer that question each and every Flyers game this season.