Petr Cech – Bouncing Back to No.1?

Prior to the head injury Petr Cech sustained in October 2006, he was widely regarded as the best goalkeeper in the Premier League. Since his return from that injury there’s been a lingering feeling that he’s never quite reached the heights of those early Chelsea days under Jose Mourinho.

Well…the Special One is back, and, according to my Keeping Model here at Differentgame, so is Petr Cech. Apart from the high-line disaster period under Andre Villas-Boas, Cech’s numbers have been pretty good but he’s not been able to match either David De Gea or Joe Hart in recent years. Until now…

My keeping model is entirely based around the location of open-play shots on target keepers face. Taking that location data into account (adjusted for volume of shots) here’s how this season’s shot-stopping rankings look so far:

Jaaskelainen bizarrely got dropped around Christmas time despite numerous clean sheets and being the No.1’s No.1 by our particular measures. That leaves Cech as the current leading goalkeeper who’s still first choice at his club.

Chelsea as a side concede less shots than almost every other side in the league. My numbers say Chelsea ‘should’ have conceded the least amount of goals in the league this season and that is indeed the case. However, Chelsea have still conceded about 6 goals less on average than the model expects.

Here’s a quick graphic of where shots on target have been conceded from. the darker the shade of red, the more shots from that zone:

Below is the league average save% from each of the 5 ‘main’ zones. ‘Main’ zones group together smaller zones with similar save%s to give me bigger samples sizes to play with for other things.

And here’s how Cech compares this year:

Those save %s are pretty impressive.

How impressive a performance is conceding 6 less than the model expects? Each shot is given a probability of resulting in a goal depending on how shots from that position have fared in history. Yes, all shots from the same position are not alike, but this gives us the ‘platonic’ idea of a shot from that position. By simulating the particular set of 91 shots on target Cech has faced thousands of times over, we can start to work out how impressive his performance has been.

Here’s the distribution of goals we could expect the average keeper to concede if facing the same shots Cech has faced:

The most likely outcome is conceding 29 goals. The blue bar there shows Cech on 23. Adding up the probabilities of conceding 22 or less we can say that there’s only about a 5% chance of bettering Cech’s performance. That’s the goalkeeping equivalent of Luis Suarez’ open-play goalscoring exploits this season.

Here’s a small collection of his saves:

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