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.
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.
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.
