Yesterday from friend of the blog 11tegen11:
The link is to this article. In summary the author has identified a set of players they deem to have positively or negatively affected their team this season. Amongst the more surprising claims is that Barcelona are a worse team with Xavi on the pitch than without. Fortunately I’ve recently run some numbers for La Liga so it’s easy for me to test this hypothesis.
First off I’ll say that I think this kind of ‘with or without you analysis’ (a tangotiger concept that has been around since at ~ 2006) has massive potential for teasing out the contribution of individual players. I even did an analysis that was remarkably similar to that in this article a few years before I started writing this blog, using the same ten game cut-off. Amongst other things it told me United were worse at attacking when Cristiano Ronaldo played. For reasons including this I decided I needed more detail before I could make anything of it.
So to some analysis. First the traditional counting numbers:
Well what do you know; Barcelona’s results were extraordinary without Xavi and merely very good with him. Maybe he is a detriment.
How about some of the more advanced numbers I usually use to evaluate teams?
Oh well, that was fun while it lasted. Barcelona are basically the same team regardless of whether Xavi plays. They take a similar ratio of shots, hence controlling the ball in the attacking zone just as often. Their opponents had similar total shot ratio’s, suggesting they were of even strength.
What changed is so obvious that the highlighting probably wasn’t necessary. If one of Barca’s opponents put a shot on target in a game Xavi started then it was 47% more likely to result in a goal than in a game he didn’t. Barca themselves scored with 10% more of their shots in games Xavi didn’t start. Try pinning that on Xavi. Seriously, give me a viable working theory, I’d love to hear it.
I guess in summary I’m saying that whilst the numbers may not suggest that Barca are better with Xavi on the pitch, there’s certainly nothing here to suggest they’re any worse.
The crazy thing is that I’m doing this in an hour with some pretty basic, freely available data and using maths that a seven year old is capable of. The post I’m responding to was written by someone who is in the privileged position of having access to opta stats and who’s website claims to be “revolutionising football statistics“. It’s truly maddening just how little of the surface is being scratched here.