Crystal ankles, paper tendons

Crystal ankles, paper tendons

A player lay crumpled in pain on the pitch as Kuku leapt up from the couch to scream at the television. Half the men on the pitch are native francophones and yet nobody is shrieking “déjà vu” louder than my agitated drinking companion.

Our reactions, hardened by repetition, have become ritual. This is how an Arsenal injury plays out.

Assumption or fact?

Arsenal and the term “injury woes” have seemed inseparable over the last several seasons. The weekly televised Reading of the List of the Injured prior to each match always felt longer when Arsenal’s turn came.

I wasn’t willing to confirm or deny it based on evidence, but like most biases, my perception of Arsenal’s physical fragility seemed true, and that was good enough. But as time has gone on, this one in particular has gnawed at me.

Right around the time Jack Wilshire was making his comeback, I was struck by just how many players on Arsenal’s roster were listed as injured, at one point very nearly half the squad. Surely this was a fluke, I thought. But what if it wasn’t? I had to know.

So, armed with time and beer, I set out this weekend to finally answer a question I’ve been pondering for years: Are Arsenal’s squad more injury-prone than their peers?

Gathering data

As it turns out, there is no good resource for historical injury data (that I know of). Individual clubs maintain their own injury lists, which they share with the FA, but these are merely snapshots in time. As players make their way back onto the pitch, their injury records are purged from these lists.

Thank goodness, then, for TransferMarkt.

I know that TransferMarkt has its fair share of criticisms, most of which are certainly valid. But these complaints always sound so much like the criticisms of Wikipedia. Sure, it’s not canonical, complete, or error-free, but it is more canonical, complete, and free of errors than just about everything else out there.

Besides, TransferMarkt fills an important niche. I’m sure Opta has the stats I want, but not at any price I’d be willing or able to pay.

Anyway. Now that I had a data source, I needed a methodology.

TransferMarkt’s injury data seemed spotty and unreliable prior to the 2008-2009 season, but in the name of completeness, I decided to gather data from 2007 through last season. And to ensure I was comparing apples to apples, I decided to collect statistics for all the clubs that have remained in the top flight since the 2007-2008 season.

So I set about gathering statistics for each athlete at each club from 2007-2013, which was made all the more difficult by the pain of merging transfer data. After a lot of careful work and cursing, I was at last able to aggregate raw numbers into meaningful stats.

As luck would have it, my assumptions were eerily accurate (that never happens). In fact, if anything, I had underestimated the rate at which Arsenal players are injured.

Days lost to injury

When I was puzzling over how to quantify injuries, the easiest metric seemed to be “days lost to injury”. To calculate this, I aggregated the total number of days members of each team spent on the injured list between the start and end date of a given season.

As is immediately apparent, Arsenal are way above the average on this metric. The rest of the teams in the league lose approximately 665 player-days to injury in a given season, while Arsenal lose almost double that amount, 1,200 player-days.

And it’s important to note just how much of an outlier Arsenal is. The average here is not heavily skewed by a few clubs with remarkably low injury rates. Most teams are clustered together quite tightly. The league-wide median number of days lost to injury is 650.

Arsenal are in a league of their own.

Days lost to injury per player

“Perhaps,” I thought, “Arsenal just have an exceptionally large squad.” This could account for the large number of absolute player-days lost to injury. So, to level the playing field, I decided to amortize this over the number of players on the roster during that season.

If anything, the results are even more striking. Arsenal’s relationship with the league average is better, but still unhealthy. And in concrete terms, this graph gives us a more relatable statistic: The average Arsenal player will spend over a month recovering from injury each season.

Yikes.

Injuries per player

But what is “the average Arsenal player”? What if this is just a case of a few big injuries ruining the mean? A serious injury like Martin Tayler’s ghastly tackle on Eduardo da Silva or Ryan Shawcross’ butchery of Aaron Ramsey adds several hundred injury days to the season total injury days and might be enough to skew the club average.

So, I decided to also calculate the number of injuries — not just their length — on a per-player basis.

Again, Arsenal consistently score worse than the rest of the league. And again, we have a relatable statistic to make this issue more concrete: Arsenal averages nearly an injury per player (0.91), while the rest of the league enjoys a comparatively modest 0.49 injuries per player.

Percentage of players injured

So, a few grievous injuries aren’t skewing things too much, but what if injury frequency is not spread evenly throughout the squad? Bad luck, as we know, does not distribute itself smoothly over everybody. Perhaps a few injury-prone players are spoiling Arsenal’s stats.

So I looked at how many distinct players were injured over the course of a season, as a percentage of the total squad size.

This last metric, coupled with the previous statistic, paint a damning picture. The brutal, season-ending injuries are not Arsenal’s issue, nor are a few chronically-injured players. Half of Arsenal’s roster will succumb to injury in a given season.

 

Conclusions

Simply put, the evidence here seems to suggest that not only are Arsenal players more likely to miss matches due to injury in a given season, but that their injuries will be more numerous and require more recovery time than those of their peers.

But that’s where it gets murky. The tricky part is apportioning blame and identifying solutions. Why are Arsenal’s footballers injury-prone?

Maybe the training staff are simply more cautious than at other clubs. Maybe the club’s youth policy or playing style predisposes the players to receive more physical punishment. Maybe — and, in light of the rumors coming out of Spain and Italy, this doesn’t seem as outrageous as it once was — other teams are doping their players to resist injury and recover more quickly.

Or perhaps this is as straightforward as it seems. Looking over the reasons cited for injury, the overwhelming majority of the injuries are training-related. Stress fractures, muscle tears, connective tissue damage… these hint at more deeply-rooted issues with Arsenal’s training and medical regime.

Perhaps the athletes are overtrained, overplayed, poorly conditioned, and suffering from the kinds of chronic injuries you’d expect in those conditions.

I don’t know. All I’m sure of is this: Arsenal really do have injury woes.