Corsi

Corsi counts every shot attempt directed at the net while a player is on the ice, shots on goal, missed shots and blocked shots alike, for their team and against it. Because the NHL does not officially track how long each team controls the puck, Corsi was developed as an indirect stand-in: teams that generate far more shot attempts than they allow tend to be controlling play and possession more often.

Corsi is usually expressed as a differential, Corsi for minus Corsi against, or as a percentage, CF% = CF / (CF + CA), with 50% representing an even split. It differs from fenwick, a closely related measure that excludes blocked shots on the theory that a block reflects defensive positioning as much as attacking pressure, and from raw plus-minus, which counts only goals, a far rarer event that produces noisier samples over a season.

Analysts use Corsi to evaluate players and lines with less noise than goal-based stats, and it has been shown to correlate with future goal differential better than past goals themselves in many contexts. The name honors goaltending coach Jim Corsi, whose shot-based tracking inspired the stat. The main pitfall is ignoring score effects: teams protecting a lead tend to sit back and allow more shot attempts, while trailing teams push for more shots, which can distort Corsi if not adjusted for game state.