July 28, 2009
Behind The Net
Pulling The Goalie

by Gabriel Desjardins

With NHL scoring rates still below three goals per game, it should come as no surprise that there are lots of close games. In fact, 72% of all regulation play during the 2008-09 season was spent tied or at a one-goal differential. From the middle of the first period through the last two minutes of the third period, a one-goal game is the most common scenario, accounting for approximately 40% of all play. The overall style of play varies very little over this time frame, and goal-scoring rates, both for the team that’s up a goal and the team that’s down, vary little.

However, at the end of the game, there is no value to having played it safe and having lost by only one goal. In the last two minutes of regulation time, scoring rates increase dramatically as the team that’s down a goal pulls its goaltender for an extra attacker. We can see that the boldest teams pull their goalie with about 90 seconds to go in the game, and at around 40 seconds to go, the goaltender is almost certainly on the bench.

There isn’t really an equivalently risky or higher reward strategy used in close games in other sports. The ‘Hail Mary’ in football comes closest, but you wouldn’t see it used on first down with a minute to go in the game – teams employ much lower risk offensive strategies until the last one or two plays of the game.

Up until the last two minutes of regulation, goal-scoring rates are roughly where they were all game, but once the trailing team puts out an extra attacker, goal-scoring goes way up. Not surprisingly, without a goalie, goals against go way up, and the rate increases as time winds down and the win value of being one goal down dwindles to zero:

It goes without saying that pulling the goalie is a good strategy. Assuming scoring rates stayed the same with the goalie in net, which is true with 90 to 40 seconds to go, the trailing team would come back to tie roughly 4% of one-goal games. With an extra attacker, teams improve their odds of tying the game three-fold, even accounting for the small number of games that they would have otherwise won had they played it safe.

Gabriel Desjardins is a contributor to Puck Prospectus and runs the statistical hockey site Behindthenet.ca. You can contact him at: info at behindthenet.ca.