Arsenal’s Injury Woes: Changing Directions

An interesting conversation broke out on Twitter tonight about the timeless mystery of Arsenal’s injury record. Personally, I’m with Raymond Verheijen – Arsene Wenger should stop holding Running Man style training sessions with chainsaws and stuff, that’s just common sense. But what other factors might be at play?

Naveen Maliakkal wondered if something about Arsenal’s style might contribute:

I’d love to see how much recover sprinting arsenal have to do since they don’t rely enough on stopping counters high up the pitch and instead trying to recover into deep positions then from rather deep positions they attempt to counter. Essentially it seems like then play a style that relies a lot on covering large distances quickly.

This piqued my interest, and I wondered if all this running backwards and forwards might be quantifiable. So I came up with a simple approach:

1. For every player, take the list of their touches in a game.
2. Split them into sets of three – (1) where the player was, (2) where they currently are and (3) where they will be next.
3. Draw a line between 1 and 2, and 2 and 3.
4. Calculate the difference in angle between these two lines, i.e. how much the player has to turn.
5. Sum all of this for each team in each season.

Picture some examples:

So, three touches, all going forwards in a straight line is an angle of zero – the player hasn’t turned at all. Turning either direction, left or right, is measured the same, and of course the maximum angle is 180° if the player makes a forward touch and then goes directly backwards to make another. The numbers below are actually done in radians, but I didn’t want to frighten anyone.

Whether or not that makes sense, what it roughly measures is how much back and forth in total each team’s bodies have had to go through. Guess who put in five out of the top ten EPL seasons?

Season Team Total Angle Turned
2014 Manchester City 117061
2013 Arsenal 114293
2012 Arsenal 112857
2014 Arsenal 112388
2013 Swansea City 112267
2011 Arsenal 111055
2014 Manchester United 110062
2011 Manchester City 110017
2010 Arsenal 109965
2010 Chelsea 109663

Arsenal appear five times in the top ten – year after year, their players are changing direction more than pretty much any other team.

Now, let me throw some caution on this approach:

• I don’t take timestamps into account, so you don’t know if there’s a second or five minutes between touches, but this is the same for all teams and is hopefully evened out in the aggregate.
• This doesn’t capture how players actually move, as they can run sideways and backwards.
• Arsenal would necessarily appear at the top, because they are a dominant, attacking team that has lots of possession and moves the ball around a lot (like the Manchesters and Chelseas you see up there). This is also true, but maybe playing well hurts.
• I haven’t checked the correlation between these numbers and historical injury data. For example Newcastle don’t place highly here but are having a nightmare this season, with 10 players out. I’ll attempt to gather some data tomorrow to see what correlation exists.

But at the very least, the fact that Arsenal hover near the top of the list every single year is intriguing, and I must thank Naveen again for pointing this out.

3 thoughts on “Arsenal’s Injury Woes: Changing Directions”

1. A says:

My guess would be that there would be a heater incidence in the gastrocnemius lateralis and medialis in those athletes with less ankle power would require greater compensation from those muscles to complete the action.. Great article! Thanks!

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2. Vaidhee says:

You should probably normalise the data with the total passes made by the team to get a more meaningful data. Because each pass adds one more data point. I’m sure arsenal ranks very highly even in total number of touches taken by players.

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1. Thom Lawrence says:

The total amount of work done is the point, though. I alluded to this in the third bullet point at the end.

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