So, I’ve been mucking about making an expected pass (xP) model recently and who should turn up in it as the season’s best progressive passing centre back but reported Everton target Michael Keane.
We all know that straight passing % provides no context to the type of passes being made by players so an xP model is a way of adding some much needed value.
The basic premise with mine is to split the pitch up into zones and see how often passes from one zone to another are successful. This will give you an xP number for each pass. Compare it to how many successful passes were actually made by a team or player between those zones, et voila…a rating can be made.
It sounds (and is) very simplistic so I wanted to do a quick eye test on it. The model tells me that Keane’s passing was particularly good against Man City last month. I only have first half footage of that game so that’s what I worked with.
I took out all the passes Keane made that the model said he had more than a 70% chance of making. This left me with what the model thought his 11 ‘most difficult’ passes were in the first half.
The footage is below. I’d like you to count how many of these passes you think Keane ‘should’ have got to his man:
I count 5. Keane made 8.
The model reckons he should have completed 5.89 passes out of the 11 made here, hence it being flagged up as a good half for him passing wise. The model doesn’t know that the opponent is Man City. My pressing metrics tell me that Man City are the most effective and aggressive high pressing team in the league. You could easily feed that into the model. You could also feed into it that City were reduced to 10 men after 32 minutes.
It’s only one quick test but I’m pretty happy with that.
The model can scout every pass Keane’s ever made in the Premier League in minutes.
It’s got a better memory than your scout.
It knows how every similar pass played in the Premier League has turned out over the last 7 years.
Your scout doesn’t.
The model can tell you clearly if a player is continually overreaching himself trying passes unlikely to come off.
The time and money this saves on live or video scouting is huge.
If you’re at the OptaPro Forum this year, come and have a chat.
Follow me on twitter @footballfactman
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