Monday, December 6, 2010

Anatomy of a 3-goal comeback

It pains me to say, but it's fun watching the Toronto Maple Leafs as a neutral observer. I also hate to say that they're winning games as your lunch-pail gang that Don Cherry loves. They can't score goals, they can't get shots on net, and half of their goaltending monster can't make a save this season.

They've had two dramatic comeback shootout wins in consecutive games, once at home to Tyler Seguin and once on the road in Washington, a game they shouldn't even have been in.

This graph is something I've been experimenting with this year to chronicle momentum changes throughout hockey games. The blue line represents the difference in Corsi, while red represents the difference in total shots on goal. Corsi, is, as many of you might know, a useful indicator of possession a team holds throughout the game. It is measured by total shot attempts by each side. The blue line represents the away team's total shot attempts subtracted by the home team's, so anything over zero benefits the road team. The same thing is done for the red line, but for shots.

The graph allows us to do two things. One is to determine which goals were scored against the flow of play, which is determined by a strong presence of possession by the team who gave up the goal a minute or two before the goal.

Goals in the Washington/Toronto game were scored at the following intervals:

WAS - Perreault: 3rd minute
TOR - MacArthur: 12th minute
WAS - Knuble: 15th minute
WAS - Perreault: 27th minute
WAS - Ovechkin: 34th minute
TOR - Grabovski: 45th minute
TOR - Brent: 58th minute
TOR - MacArthur: 59th minute

If you line up each of those goals on the graph, you'll find that both of the Capitals' second period goals fit in the 'goals against the flow of play' mantra. These goals are tough to rebound from and account for, in my crude estimates, roughly 25% of goals and work the same as points of turnovers or fast-break points work in football and basketball respectively. The team with more goals against play is generally going to win since they scored at a time they weren't supposed to.

The Leafs hit their lowest moment. They were down 4-1 to one of the best teams in the NHL on the road, but, the scrappy, lunch-pail team didn't fold. If you check the graph between the goal and the end of the game, you'll find this:

Except for a brief scare in the final minute, you can see that the Leafs fought and held the bulk of possession directly after the second Mathieu Perreault goal. While they finished regulation -6 Corsi and -7 shots against, it's still a pretty impressive comeback.

After the first period, the Capitals had 64.5% of possession and 63.2% of the shots. From the 4-1 goal to the tying goal, the possession margin was shrunk to 52% in favour of the Caps.

Also, Jonas Gustavsson's save off of Perreault coupled with Mikael Grabovski's crazy spin move aren't bad to have if you're trying to win a shootout.

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