Arsenal

EGMAYO, An Injury Impact Metric

Thom Lawrence, , , , Leave a comment

Different injuries have different impacts. In this article I am going to look at how historical injuries have affected teams from the perspective of expected goals. Given each squad member’s xG per 90, and the number of games they missed, what’s the total amount of xG that was sidelined in a season?

I call this metric EGMAYO: Expected Goals Missed due to the Absence of Your Offence. Here are the top 10 EPL seasons by EGMAYO:

Season Team EGMAYO
2014 Arsenal 26.9
2010 Arsenal 23.3
2013 Arsenal 22.9
2012 Manchester City 19.4
2014 Liverpool 17.7
2013 Manchester City 17.4
2014 Manchester City 17.2
2014 Newcastle United 15.0
2011 Manchester United 14.8
2012 Manchester United 14.2

This indicates it’s not necessarily overly dramatic to point out that Arsenal’s injuries have had a big impact. Their lowest EGMAYO season was 2012, scoring 7.1, against an overall EPL average since 2010 of 6.7. Man City were title runners-up in their worst EGMAYO season:

Season Team Player Games Chance Quality per 90 Chance Quality missed
2012 Manchester City Jack Rodwell 18 0.36 6.42
2012 Manchester City Sergio Agüero 7 0.45 3.18
2012 Manchester City Micah Richards 22 0.12 2.67
2012 Manchester City Maicon 16 0.15 2.43
2012 Manchester City Mario Balotelli 4 0.53 2.12
2012 Manchester City David Silva 3 0.23 0.69
2012 Manchester City Aleksandar Kolarov 6 0.10 0.57
2012 Manchester City Vincent Kompany 7 0.06 0.42
2012 Manchester City Samir Nasri 2 0.16 0.32
2012 Manchester City Javi García 3 0.09 0.28
2012 Manchester City James Milner 2 0.12 0.23
2012 Manchester City Pablo Zabaleta 1 0.08 0.08
2012 Manchester City Joleon Lescott 2 0.02 0.03

Obviously it’d be far more interesting if we could better capture Vincent Kompany’s 7 game absence from City’s back line, or David Silva’s expected assists missed in his 3 games, but we’re not there yet, which brings me to:

Caveats

Sometimes my kids go up to a box of toys and just empty it onto the floor, play briefly with a couple of things, and then bog off to let mummy and daddy deal with it. Perhaps I haven’t made this abundantly clear, but this is very much my approach to football stats. I enjoy cutting data up, throwing it haphazardly on the floor, and seeing what it looks like, especially to other people. I intend to return to this later to clean up, but I’d like to make a few things clear:

  • This metric takes no account of the squad members that come in and replace injured players. Obviously these replacements have their own output in terms of xG, which may even exceed the injured player. Ideally, we would capture all of this in a similar way to Chad Murphy’s model, or even in more detail to capture the strength of schedule faced during each injury.
  • It takes no account of the importance of midfielders, defenders or goalkeepers. It’s only interested in the xG per 90 of a injured players, and therefore is weighted heavily in favour of strikers. I’m merely using it as one way to look beyond raw injury stats, I’m not saying it’s the final destination.
  • The EGMAYO calculation uses the same season as the injury for xG per 90, so players injured early on, or starting the season injured, aren’t measured particularly accurately.

So, I know all that, don’t point it out – I’m working on it. I just want to get this up for discussion’s sake, because it adds more context to articles like this in the Telegraph today. Comments welcome here, or on Twitter.

EGMAYO, An Injury Impact Metric

101 Weird Injury Stats

Thom Lawrence, , , Leave a comment

Everybody likes lists, and I’ve become interested in injury data, so today I’m going to attempt to give you ONE-HUNDRED AND ONE FORTY-THREE unbelievable and fascinating injury stats!

Some caveats before we begin: I only have access to data that’s public on the web, there’s a lot of junk so in some cases I’ve disregarded data that doesn’t seem to add up, and I’ve avoided including career-ending (or indeed life-ending) injuries and illnesses in individual stats, although they will show up in aggregate stats.

I should also point out that I am not a doctor, so I am not going to attempt to group injuries together in sensible ways beyond what’s absolutely obvious. I literally do not know what the knee bone is connected to. Do knees even have bones? What are bones? I don’t know, I only have data and find the human body disgusting. Let’s move on:

  1. Most injuries suffered by a player: 41, Franck Ribéry
  2. Most injuries suffered by a team: 409, Werder Bremen
  3. Longest individual injury: 1064 days, Shaun Barker
  4. Most days spent injured: 1568, Tufan Tosunoğlu
  5. Most days lost by a team to injuries: 15482, Werder Bremen
  6. Most injured body part: Knee, 2694+
  7. Shortest average injury: contused laceration, 4 days
  8. Longest average injury: fractured tibia and fibula, 246 days
  9. Shortest recovery time from fractured tibia and fibula: 44 days, Jan Fitschen
  10. Shortest recovery time from fractured tibia and fibula that I can check by Googling: 128 days, Neil McCann
  11. Longest recovery time from fractured tibia and fibula: 807 days, Christian Muller
  12. Most games lost in total across all leagues to an injury: 34366, Cruciate ligament rupture
  13. Most recurrences of same injury: 10, Tim Petersen, Knee injury
  14. Most different types of injury suffered: 33, Sven Bender
  15. Number of times I’ve got worried I’m not going to get to 101: 1
  16. Most injuries by league since 2012/13: 1081, German Bundesliga
  17. Least injuries by league: 231, French Ligue 1
  18. Most games lost to injury by league: 8954, English Premier League
  19. Least games lost to injury by league: 1569, French Ligue 1
  20. Most days lost to injury by league: 58457, English Premier League
  21. Least days lost to injury by league: 10201, French Ligue 1
  22. Most injuries suffered by a team in a single season: 79, Werder Bremen, 2008/9
  23. Most games lost to injury by a team in a single season: 294, Werder Bremen, 2008/9
  24. Least games lost to injury by a team in a single season: 6, Montpellier, 2011 (not entirely sure I trust the data)
  25. Most injuries suffered by an EPL team: 266, Arsenal
  26. Most games lost to injury by an EPL team: 2184, Arsenal
  27. Most games missed by an EPL player: 250, Abou Diaby
  28. Most different players injured: 85, Arminia Bielefeld
  29. Most different players injured in a single season: 30, AC Milan, 2011/12
  30. Most different players suffering same injury: 28, Austria Vienna, Illness
  31. Biggest outbreak of illness or flu at a club: 11 players, Austria Vienna, 2009
  32. Most different players suffering same injury in a single season: 13, Dundee Utd, Knee injury, 2014/15
  33. Most seasons a team has experienced the same injury: 10, Arsenal, Thigh problems
  34. Number of players relapsing within 1 game: 32, e.g. Vincent Kompany
  35. Longest time between relapses: 2732 days, Leighton Baines, Malleolar injury, 2007 & 2015
  36. Number of people who believed I would actually be able to come up with 101 of these: 0
  37. Fewest games missed for a title-winner: 6, Manchester City, 2011/12
  38. Most games missed for a title-winner: 351, Bayern Munich, 2014/15
  39. Most games missed or a relegated team: 318, Queens Park Rangers, 2014/15
  40. Fewest games missed for a relegated team: 40, Blackburn rovers, 2011/12
  41. Highest coefficient of variation among injury layoffs (10 or more incidences): 302.5%, Pneumonia
  42. Lowest coefficient of variation among injury layoffs:  37.8%, Cruciate ligament surgery
  43. R2 of career games missed to challenges (tackles, aerials, take ons): 0.0128

Okay, so, ran out of steam a bit and I think I’ve tweaked my anterior SQL ligament. If you are not satiated and have any particular stat requests, just ask on Twitter. I will of course be attempting to do some more serious work with this stuff in the coming weeks, but I just wanted to see what the data look like.

In the meantime, sort yourselves out Arsenal and Werder Bremen, you need to learn what serious pain is.

101 Weird Injury Stats

Arsenal’s Injury Woes: Changing Directions

Thom Lawrence, , , 3 Comments

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:

total-angle

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.

Arsenal’s Injury Woes: Changing Directions