Yes, the Sounders were among the most-injured teams in 2018

I started this search a while ago: is there a good source for data on MLS injuries?

It was my white whale. It’s the coming together of my job in data science-y public health stuff and my enthusiasm for the Seattle Sounders. It’s something that I rarely see actual analysis of, but hear a lot of speculation about. It’s information that might actually prove useful to the team (although probably not).

But there really isn’t any data, let alone data across teams and over time, on injuries in MLS. Like, really not any. I know because I’ve now reviewed the sports medicine academic literature, and couldn’t find anything that even suggests the existence of such a dataset. I’m pretty confident that the league simply does not keep track of injuries in a consolidated way. So I set out to do it myself!

There is the scattered news release, the surprisingly-unofficial injury section on MLSSoccer.com, and some websites that appear to have bits and pieces, but the best source I know of (and please tell me if you know a better one) is the match preview page of any given game. It at least has the requisite information (i.e. who was absent, why and when), and is available going back in time for many years. Much to my anguish however, it is not consistently formatted game to game and is extremely tiring to compile together systematically. But I must, so I do (using rvest... I’m not that crazy).

I’ll call it a work in progress, but I’m now the proud owner of a spreadsheet containing the 4,715 reported injury-related absences, 127 suspension-related absences and 67 international duty-related absences reported through the match previews from the 2017 and 2018 MLS seasons. It probably has some minor errors in it, but let’s call it 99%.

Here’s a neat graph of the data:

What we’re looking at here is the number of injury-related absences reported by the Sounders on each match day in the last two seasons (black), compared to the daily average for the rest of the league (red). The smooth lines are just a loess fit, which is basically a fancy moving average.

You can see some interesting trends. For one, the league at large (in red) tends to start on a healthy foot, and get progressively more injured over time each season. In 2017 there was a small decline right at the end of the season, but in 2018 it kind of continued right into the playoffs from just over two absences per game at the start of the season to just over four on the last day (2017 peaked at around 3.5 in August).

The Sounders, on the other hand, have been counter to the trend. Especially in 2018, we started off with lots of injuries and gradually got healthier. On the first match of 2018, we had five players out or questionable due to injuries. That number swung up and down, but the average remained above the rest of the league for months last year. Things started turning around in July, when the average number of players absent declined from five per game down to 3.5 by September. It’s not surprising that this coincides with the Sounders’ epic unbeaten run from July 4 to Sept. 15, 2018. A similar trend happened in 2017, as the Sounders got much healthier through the late summer, before picking up a few more knocks going into the playoffs. In 2017 too, this went along with an extraordinary unbeaten run (June 21 - Sept. 16).

But were the Sounders really that out of the ordinary to have so many injuries? Here’s the totals for the last two seasons:

I sorted this by the total number of injury-related absences in 2018, so you can see the rankings. Poor-ol’ Real Salt Lake, they suffered 230 player-days of absence last year, which put them in first ahead of Chicago Fire (198 absences), Minnesota United (176 absences) and Houston Dynamo (158 absences). The Sounders turned out to be No. 5, with 153 total absences, or an average of 4.5 per game. In 2017 (a substantially healthier year all around) the Sounders ranked 13th (84 absences), and RSL again was first (158 absences). This is of course combining players listed as Out, Doubtful or Questionable. The Sounders seemed to have a large portion of players listed as Questionable.

But who were those unfortunate players? We all know Jordan Morris was out with an ACL tear all season, but here’s the injury totals by player for the Sounders:

Second to Morris’ 34 missed matches was Handwalla Bwana, who missed 16, followed by Victor Rodriguez (15). In 2017, Brad Evans missed 19, Ozzie Alonso missed 11 and Aaron Kovar missed nine. Again, there’s kind of a lot of Questionable rather than Out. This could be either the Sounders trying to “soft play” injuries, or players picking up nagging little injuries that hang around. That’s probably grounds for a separate analysis.

But what’s the point of all this? I can think of a few things.

First, I think it’s useful for setting expectations. Two-hundred, thirty-eight player-days lost over two seasons gives us a tidy rule of thumb that we should expect 3.5 players on any given game to be either out, questionable or doubtful. It’s hard to predict whether those players will be starters or depth, but you can see for yourself how that distribution shakes out.

Second, it’s really interesting to me how cleanly the Sounder’s most successful periods of time correlate with their healthier periods of the last two seasons. This shouldn’t be super surprising, but a follow-up analysis about the points lost due to injury now seems within reach (don’t worry, it’s coming).

Third, this lends credence to that explanation about the slow starts. It’s been a common narrative: someone says the Sounders are a bad first-half team, to which someone quickly replies “yeah but the injuries.” Well, when I saw how much healthier the rest of the league was than the Sounders (not just how unhealthy the Sounders were, but how they compare to the norm) in the first graph, I found a new sense of forgiveness to the front office about how we began the last two seasons. When the average opponent has nearly three more players at their disposal, it’s not hard to reason that the Sounders were at a disadvantage.

It’s also notable that at the peak of their 2018 glory, the Sounders were still only on par with the injury rate of the rest of the league. It bucks any narrative that we were just lucky to be full-strength for that win streak. Going into 2019 with essentially the same, but so-far-healthier, roster, this observation bodes well for the season.

But there’s also another reason that this is useful. If history has the tendency to repeat itself, then we can use this to reasonably anticipate what might happen in 2019, and where our depth chart might be hurting the most when the inevitable occurs. I look at the chart above and I see a lot of attacking midfielders with high absence counts. Maybe it’s not fair to count Morris’ 2018 injuries, but he still missed eight games due to injury in 2017 (4th most that year). Adding together Morris’ 2017 number, plus Rodriguez, Lodeiro, Shipp, Smith, and Bwana, that’s an average of 10.3 games missed per person (62 total game-day absences / 6 players) from the players who could reasonably be in the attacking band of three in Schmetzer’s go-to formation next year. To me, this says attacking midfield needs more depth.

For comparison, the six main options in the back line (Nouhou, Smith, Marshall, Torres, Kim and Leerdam) were listed as injured for a combined 30 games in 2018, or five per player. Forwards (Ruidiaz, Morris-17 and Bruin) combined for 13 absences in 2018 (4.3 games per person), though we have yet to see a full season from Ruidiaz. Incredibly, our options at defensive mid (now Svensson, Roldan and Delem) registered zero injury-related absences in 2018 as far as I can tell, which makes me feel pretty safe about that holding midfield role.

So there’s a lot to do with these data. I think the first conclusion is that we should set our expectations realistically at 3.5 absences per game. The second is that staying healthy really matters. It might be something we already knew, but this starts to say so in real data. When the next transfer rumor comes along, I’ll be checking out their injury history. Most importantly however, this should be information to fuel our raging comment-thread debates about whether the Sounders should sign a speedy winger or second forward. We need to hedge against the injuries.

Until next time,

- DMP