It's a cliche that goalkeepers are mad. But this new paper shows that they might also be plain wrong. A group of Israeli academics looked at a sample of penalty kicks from top matches around the world, and found that keepers' chances of saving them would be much higher if they stood still, rather than diving.
They estimate that a custodian of the onion bag who kept still would have a one-in-three chance of making a save, compared to a one-in-seven chance if he dived.
However, keepers very rarely stay put. In 93.7% of the 311 kicks studied, they dived, even though 28.7% of kicks went down the middle of the goal.
This suggests the best goalkeepers don't optimize their chances of saving spot-kicks. Why not?
There are several possibilities*.
One is that the purpose of diving is to put pressure on the striker. A striker who knows the keeper will dive must either aim for the corner of the goal or try to dummy the keeper, which adds to his chances of missing. But a striker who knew the keeper would stay put would possibly have an easier job.
Another possibility lies in the mix of social norm and regret minimization. A keeper who dives and fails to save a pen gets no blame. He's expected to dive and miss. But one who stays still and fails would get stick: "why didn't you try to save it?" he'd be asked.
Perhaps keepers put a higher priority upon not getting flak than upon maximizing their chances of saving. As Keynes said, it is better for one's reputation to fail conventionally than to succeed unconventionally.
This problem, though, might not be confined to goalkeepers. Governments and bosses are also expected to do things, even though inaction might be best. "Just stand there" might be good advice for them too.
* For example, a diving save looks great, and keepers value the small chance of this more than they do the bigger chance of a routine save. Or perhaps there's a social norm - revealed by the stick Nani got recently - against making one's opponents look stupid, which a standing save would do.