I started typing a whole thing in another thread, and then I realized I was majorly thread-jacking with a new topic and should track down the pitching injury thread.
I've copied below the post I was responding to in that thread, not to put
@Sandy Leon Trotsky on blast here (I like SLT — good poster, would read again), but as a clearly put example of a very common idea that people often express on this board, especially in discussions of Whitlock's health issues: the idea that relief pitching is safer than starting for injury-prone pitchers. And I just don't see a ton of evidence for it.
Here's what SLT said, talking about Bryan Mata:
And in response, I wanted to point out that Mata had been moved to the bullpen late last year, and pitched in the AFL as a reliever — when he got hurt — and was pitching in a relief role in ST — when he again got hurt. So arguably he's also shown he gets injured as a reliever.
Like Whitlock, Mata has a lengthy injury history. Both pitchers have pitched in different roles in their careers as professionals. I do not think we can know from the information that we have (e.g., that Whitlock's healthiest season
in the majors came as a reliever) that their roles contributed to their injuries. It's not as though we can run 10,000 Monte Carlo simulations of a pitcher's career to come to a definitive, statistically probative judgment of whether he is more likely to remain healthy in a given role.
Starting pitchers get hurt a ton, but relief pitchers
also get hurt a ton. Both roles have pros and cons from a health standpoint, of course: starters have to pitch more innings, but they get a schedule with rest built in; relievers throw considerably fewer pitches per outing, but they have to pitch at 100% intensity on an unreliable schedule, sometimes with minutes' notice, sometimes on back-to-back days.
I grabbed some data on IL stints from ESPN.com, which I've tidied up and shared
here. This listing only contains players
currently on the major-league IL; so, for Boston, Garrett Whitlock and Bryan Mata are included, but Bello and Pivetta (who have been on the IL and returned) are not.
Roughly speaking, there are 5 * 30 = 150 SP slots and 8*30 = 240 RP slots active at any given time; so relievers are ~61% of pitchers. And there are 68 starters and 94 relievers on the various ILs; so relievers are 58% of IL'd pitchers. ~31% of starting pitchers and ~28% of relief pitchers in the majors are on the IL.
Those percentages are all pretty close, to my eye. This is just not very consistent with relieving being meaningfully safer than starting. It is consistent with pitching (in any role) being quite risky.
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Now, maybe you could make a case that an injury-prone pitcher (to the extent that isn't just a synonym for "pitcher") might be better slotted into the bullpen
for the good of the roster because it's easier to reshuffle roles in the bullpen in the wake of an injury than it is to get your depth starting pitchers lined up, etc., when one goes down. If that were the case, and we could confidently discern which pitchers were especially injury prone — a massive, massive "if" — it might indeed make sense from a roster standpoint to pitch those pitchers in relief. However, that's quite a different claim than the argument that a pitcher who gets hurt as a starter would not get hurt (or would get hurt less frequently) as a reliever.
TL; DR. I do not see a lot of evidence that pitching in relief is
safer for a given a pitcher than pitching in the rotation. Am I off base? Is there such evidence, and I am ignoring it?
