Left, right, left, right…

A couple of weeks ago Ben Torvaney wrote an interesting piece about left footed players converting chances at high rates from the right side of the pitch.

Ben put forward a number of possible theories as to why this might be the case.

I’m going to suggest another one using Steve Fenn’s jazzy viz of my goal keeping data. The data is from the Premier League (nearly 6 seasons worth) rather than the Bundesliga data Ben used, but I think it’s still relevant to the discussion.

In the Premier League overall save % from these wide sections of the pitch on both sides is about 82%. However, as you’ll see from the screenshots, goalkeepers seem a lot more aggressive with their positioning for saves when facing shots from the right side of the pitch (or left as they themselves look at it).

Yes folks, I’m back in comfort zone (CZ) territory again. I’ve shaded the CZ here, so anything outside that I’m considering aggressive. Just 40% of saves are made in the CZ from shots on the right side of the pitch compared to 55% from shots on the left side of the pitch:

New CZ shaded left right viz

These wider, more aggressive attempted save positions not only expose more of the goal, they also reduce reaction time as they’re closer to the shooter.

Also, left footed shots from the right hand side of the pitch (as the shooter looks at it) are more likely to start to move away from the keeper before curving back towards goal than a shot with the right foot. I think this may be a thing.

The graph also shows a slight trend for more goals being conceded at the far side of the goal on the side where keepers are more aggressive:

Where goals go into the netWhy do goalies keep so lopsidedly? It seems there’s a bit of a trend for right handed goalkeepers to be more aggressive in their positioning when facing shots from their left, and left handed keepers to be more aggressive in their positioning when facing shots from their right. As the majority of keepers in leagues are right handed, it might be causing the skew Ben talks about.

Colin Trainor’s piece about keepers over-protecting their near posts inspired much of my later research into keeping data. Give it a read.

Follow me @footballfactman on twitter

 

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One Response to Left, right, left, right…

  1. Russell says:

    Good article. Could you possibly explain what you mean by: “These wider, more aggressive attempted save positions not only expose more of the goal..”?

    I get that moving away from the goal line leaves goalkeepers more vulnerable to chips, and agree with your point about reduced reaction times, but doesn’t moving closer to the shooter expose less of the goal, not more, unless they’re doing it in a really amateurish manner? I played in goal and we were explicitly coached to move towards the shooter in order to “narrow the angle”. Apologies in advance if this is a daft question.

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