This should serve as a nice summary for the posts I’ve done about penalties. I should again mention that I’m indebted to Infostrada, in particular Simon Gleave, for the data in these posts. If you want to bypass the summary and get to my thoughts then skip to the end.
I – there’s some season to season variation in the number of penalties awarded. There’s some season to season variation in penalty conversion rates. In both cases this variation looks a lot like random noise, although there does look to be a weak upward trend in the number of penalties that are awarded (link)
II – more penalties are awarded as a match progresses, I think this probably mirrors the distribution of shots throughout a game. The time a penalty is awarded has no impact on how likely it is to be scored (link)
III – some referees award more penalties than others. Only one (Mike Dean) does so at a level that is statistically significant (link)
IV – Hurray! I found something that seems to statistically significant! Home teams are a) far more likely to be awarded a penalty and b) more likely to score them than their opponents. The sample is too small to determine whether the game state (score) has an effect on conversion rates (link)
V – The correlation between how much a team has the ball and the proportion of penalty decisions in their favour is quite strong. No team (with the possible exception of Chelsea) has a demonstrable ability to take, or save penalties. Manchester United get awarded more penalties than we’d expect (link)
VI – Pick a player. Any player. In all likelihood that player is no better at taking or saving a penalty than any other player you could have picked. The lone exception – a player taking his first penalty (link)
All of this leaves me with two questions:
Given that they don’t discriminate between team skill then why do we use penalty shootouts to decide games? This question was, however, beaten to death following the Champions league final in a much more eloquent manner than my stream of conciousness will afford so I won’t go into it any further.
What really intrigues me is this: there are only so many components that go into making one striker better than another. These posts strongly suggest that shooting is, at most, a very minor component. So what are we left with?
The ability to get into the position to create a chance in the first place is, I’d suggest, a (if not the) major component.
Heading? Instinct tells me the spread is probably similar to that of shooting, I’d be willing to look anyway though.
Knowing when to shoot and when to pass/try to create a better opportunity? This would be a nightmare to look at statistically but I think would probably correlate well with positioning.
The ability to kick with their ‘wrong’ foot?
Similarly when we’re looking at ‘keepers, if they’re all essentially as good as each other at stopping a shot from twelve yards then what are we left with?
Knowing when to leave/come and claim a cross?
Distribution of the ball on goal-kicks/from the hands?
Making themselves available for a back-pass?
I’m probably missing some here but I think I’ve made my point – we shouldn’t necessarily be judging ‘keepers on how often they stop shots as the spread of talent is likely pretty small. Instead we should focussing more than we currently are on the other things they do and how that adds value to a teams performance.
The surface is barely being scratched here but at least we’re coming out with a little more knowledge than we started with. I hope so anyway.