Alex Diaz


Illustrating score effect by period in the NHL

It’s well-established that a team’s shooting numbers vary based on the period and the state of the game. As a team falls behind, it plays more aggressively, and vice versa. You can see it clearly in these graphs from the last five seasons. Each graph measures the league average even-strength Corsi percentage for the entire season, by score difference (down by two or more, down by one, tied, up by one, up by two or more)

Two consistent patterns appear in every season:

  1. Possession declines with a lead and increases with a deficit.
  2. The first and second periods are very similar, but in the third period there is a remarkable change in the magnitude of the differences in possession

Note: The 2012-2013 season was shortened by a lockout; while the overall conclusions are the same, the differences in the third period are much starker.

Category: Analytics, Hockey


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