Eurocup 2008 Soccer penalty shots – A detailed analysis

Posted on Saturday, June 14th, 2008 at 1:30 am
Filed under: The Sports Rant
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So I’ve just watched Romania and Italy play to a 1-1 tie. Italy desparately needs to win in order to make the next round. But, while Italy had all sorts of scoring chances, Romania was given a penalty shot with about 10 minutes left in the game.

Have you thought about the odds of scoring a penalty shot in soccer? The net is, like, the size of an aircraft carrier. And the goaltender is tiny. You’d figure that the percentage of succesful penalty shots (resulting in goals) would be 99.999999%. But it’s not. Heck, when a game goes into overtime, then shootouts, teams only score 3/4 goals out of 5 kicks. If they’re lucky/decent. I’m horrified. So I’m wondering what kind of statistics drive the penalty kicks. For simplicity, let’s divide the net into possible shots/regions and assume that the professional soccer players (such as those playing in Eurocup) can put the ball werever they want. I realize this is stretching things, since some of the greatest Italian players tended to (inexplicably) shoot the ball OVER the net during crucial penalty shots. I’m going to ignore this. Let’s say the shot regions are:
left
center
right
Not too difficult to understand, right? Sure, they could shoot high left or high right and the goaltender would never have a chance, but no one does this. I’m guessing that it’s considered “cheating” or “unsportsmanlike”. Soccer is a strange sport. Anyway, so the ball can go to one of three locations, and any of these locations results in a goal (obviously, I’m going to ignore the no-talent Canadians who shoot outside the net…). The goaltender can only be at one of these locations. This really makes the math easy. Basically, the goaltender guesses which location the shooter will chose, and goes there. Brilliant. Why don’t we just flip a coin? Anyway, he’s got a 1 in 3 chance of being correct. Using this analysis, about 66% of penalty shots should go in. From what I’ve seen, this is about right. The thing is, the goaltender is more likely to let in a goal, but he doesn’t want to look stupid. Standing in the middle while the ball scoots in the left or right side would look bug-ugly stupid. So they normally guess left or right and leap frantically in that direction. If I was a professional soccer player taking an important (or any) penalty shot, I would always shoot down the middle.

To be honest, anything they do is all right, as long as they don’t do this…

The Italy/Romania match image was taken from tsn.ca, and seems to be copyrighted by Boris Horvat. We do not own the image. No infringement is inteded.