Are Tigers pitchers injured an unusual amount?

Another day, another Detroit Tigers pitcher gets injured: just this week Matthew Boyd got sent away for Tommy John surgery, and soon after that, Reese Olson took a comebacker off the leg. Fortunately, Olson appears good to go in his next outing, but add to those the long-term loss of Eduardo Rodriguez, Alex Faedo, and Spencer Turnbull. Then we have Tarik Skubal just about to return to the rotation this week after missing the first three month. Casey Mize probably won’t be back until the 2024 season as he rehabs from Tommy John surgery. And finally, Matt Manning took a comebacker off the foot back in mid-April and has only just returned to the rotation. That’s not even all of them as we could add Beau Breiske, Trey Wingenter and others to the long list.

This got me thinking: is this an unusual situation? Do other teams have to deal with this? Are Tigers pitchers somehow cursed? And, how much does having continually-injured pitchers affect a team’s winning percentage?

Methodology

Data were gathered from Fangraphs’ Roster Resource page, an example of which is here. I selected six teams that go from terrible to mediocre to great, and sorted through the data from the entire 2022 season and the 2023 season through June 28. Things to keep in mind:

• The data set includes pitchers that may be on the 40-man roster, but haven’t been “impact” pitchers at the major-league level. An example of this is Freddy Pacheco for the Tigers; he’s never thrown a pitch in the big leagues, but he’s on the Tigers’ 40-man roster right now (he’s on the 60-day IL).
• I thought about taking pitchers like that out of the data set, but I didn’t know other teams’ players as well as the Tigers’, so I just left everyone in that was listed.
• For someone who’s out a year and a half for something like Tommy John surgery, they’re “officially on the IL” from the first day of the season to the last. The offseason doesn’t count.
• The dates used were the days the pitcher were on the IL; this might be “retroactive” to a certain date.
• Some of the injuries were listed as “undisclosed,” and I have a hunch those are Covid-related. That doesn’t really fit into the type of injury paradigm we’re interested in here, but I left it in anyway because I didn’t want to pick-and-choose.
• I also didn’t discriminate betwen injuries that were probably due to the act of pitching (e.g. elbow inflammation) vs. time lost, say, getting hit by a comebacker.

Alright, let’s take a look at the data.

Charts and Graphs

Here are the raw numbers of days lost to injury.

Again, I tried to get a range of teams here: our very own division-leader is Cleveland, an average National League team is Philadelphia, Atlanta is a good team, Washington is a bad team, and I threw Tampa Bay in there because I knew they’d be interesting.

And, as you can see, holy cow, do the Rays lose a lot of days to pitcher injuries! Last year it was significantly more than Detroit, and this year it’s about even. It could be that my mix of teams is skewed one way or another; you’re free to investigate this yourself if you want to see if I’m way off.

Washington had it bad last year but has been a bit better than Detroit this year; Stephen Strasburg represents a lot of those days. Cleveland has had a decent run the past year and a half when it comes to pitcher injuries, as it turns out.

While we could sit around and talk about how many days are lost, the big question is, “Does this affect the team’s record?” So I graphed the team’s winning percentage against pitcher-injury days to see if I could find out.

For the 2022 season, it appears as if, the larger the number of pitcher-injury-days a team has, the worse its record will be. It’s not the strongest correlation (R² = 0.36), but it’s worth noting. That weirdo dot in the top-right pulling the slope up a bit? Tampa, of course. As it turns out, a seemingly inexhaustible supply of talented pitchers diminishes the effect.

For the roughly half of the 2023 season played so far, the correlation is much looser (R² = 0.09), so the slight upward slope you see might not mean much of anything. Plus, my conjecture is that, as the second half of the season wears on, those pitcher injuries really start to have a cascading effect on the team’s ability to win. One could split the data from the 2022 season into first half and second half to see if this idea holds any water.

I also got to thinking about extended absences and their cumulative effect. If you have pitchers going down and coming back in two weeks, you can paper-over that with a spot start by a reliever, throwing a bullpen-day parade, or bringing up someone from the minors for a start or two. But if someone that a team thought they were going to depend on happens to be injured for most or all of the year, I imagine that’s much more of a burden on the team.

It looks like the numbers bear this out, if you graph winning percentage against the average number of days each IL stint lasts.

These are much tighter correlations (the R² values are much closer to 1), so I think this might be a better predictor than just raw number of days lost. Again, the correlation is a little looser for 2023 but there might be a cumulative-effect thing happening.

Conclusions

1. Is the Tigers’ situation unusual?

A little, but Tampa Bay seems to get by alright… as they usually do.

2. Does this have an effect on team outcomes?

It looks like the duration of individual injuries has more of an effect on the team’s winning percentage than just the number of days lost.

3. How can the effects be combated?

One, it helps when it’s not your best pitchers getting hurt. Two, the Tigers need to continue to build a deep stockpile of pitching depth in the upper minors. As for whether there are issues in training and conditioning? Those are hard to parse. Some of the Tigers’ injuries are obviously just flukey things like comebackers at the pitcher. With Scott Harris overhauling the training and biomechanics departments, we’ll see if that pays any dividends in the years ahead, but it will be hard to sort out any effect.