Baseball Therapy: Let Him Pitch!

We know that the Mets are going to the playoffs. We know that Matt Harvey plans to pitch in the playoffs. But should he? Harvey, of course, missed the entire 2014 season after Tommy John surgery, and a couple of weeks ago there was a small kerfuffle over whether Harvey would be "allowed" to pitch in the postseason. It seems now that the issue has been resolved and the answer is yes.

It looked for a brief moment that we were headed for a repeat of the 2012 Stephen Strasburg saga. For those who have blocked that one out of their memories, Strasburg had Tommy John surgery in 2011, and in 2012, the Nationals decided that he would only pitch 160 innings and would not be on the postseason roster. The Nats eventually lost the Division Series three games to two to the Cardinals. It's hard to say that Strasburg would have been the difference, but … they would have won the World Series that year with Strasburg.

The logic then was that Strasburg needed to take it easy during his first year back, and that to push him would be to risk him for the next few years. It might mean that the Nats were punting a bit of their chance in 2012, but of course, the Nats were a young team on the upswing. Better to make sure of a healthy Strasburg for the 2013, 2014, and 2015 playoffs. At least they made it to the 2014 playoffs. The number we heard all summer was that Strasburg would pitch 160 innings, and no more. (He ended up pitching 159 1/3, plus one in the All-Star game.) The rumor swirling around Harvey was that he was supposed to max out at 180 innings, but apparently that's not a very firm limit. And it looks like the Mets will have Harvey on the mound for Game 1 or 2 of the playoffs.

Intuitively, the idea that teams should be careful with their returning TJ patients makes sense. We know that the best predictor of pitcher injuries is previous injury, so a returning pitcher already has a strike against him in avoiding the DL. But is an innings limit the best way to keep a guy from having to take time off? We know that within a season, it appears that individual outings with super-high (more than 115) pitch counts are associated with both a risk of injury in general and specifically for the kind of catastrophic injury that Harvey suffered to begin with. But can pitching too often be a problem by itself, even if the pitch count within each game is reasonable?

And what's up with the innings limit anyway? As has been pointed out, ad nauseum, an inning is a very imperfect measure of how much a pitcher has had to work. A pitcher might throw three pitches or he might throw 30 to get three outs. It all goes in the record books as one inning. And where did the number 160 or 180 come from? It smacks of someone picking a round number that "sounds about right." Maybe there's some justification for it though. Can an innings limit help keep a pitcher healthier?

Warning! Gory Mathematical Details Ahead!
I isolated all pitchers who had an elbow injury that necessitated the use of the 60-day DL. These weren't all TJ cases, but most were and it's not like a non-TJ case comes with a note that says "Let him throw 300 innings." I then looked for pitchers who came back the following year and were primarily starters, and counted how many innings they threw (majors, minors, and postseason), how many batters they faced, and, at least at the major-league level, how many pitches they threw in the year after their TJ. I then looked to see whether any of those usage indicators had any relationship to whether the pitcher had (1) a trip to the DL in his second year after TJ, (2) another elbow injury, or (3) another catastrophic elbow injury.

I set up several binary logistic regressions. For example, was the number of innings a pitcher threw related to his chances of another injury? Nope. His chances of an elbow injury? Nope. His chances of landing on the DL? Nope. If innings didn't work, did using batters faced change things? Nope. Number of pitches was no help either. I even looked at severe shoulder injuries. Nothing there.

Maybe I had too short of a time horizon. I had been looking at whether an innings cap in the first season back made a difference in the second season back. Maybe I needed to look at the third season back to see the effect. Nope.

I should point out that the sample size was 85 for the two-year window and 78 for the three-year window, which isn't huge, but it's the sort of sample where if there's a decently big effect, we could at least see something peek through the noise. (The initiated will know that I am talking about statistical power here. The more cases in your sample, the better your odds of finding a smaller and smaller effect. There also comes a point at which you might be able to detect a tiny effect, but if it's that small, who cares?)

But the message was pretty clear. There does not appear to be any data-based justification here for an innings cap on a starter who has had Tommy John surgery. It is entirely possible that he will get hurt in the next year. The best predictor of injury is still previous injury, and by definition our Tommy John patient has had a previous injury. But capping his innings when he comes back neither increases nor decreases that risk.

I suppose I should add a disclaimer about "within the normal bounds of decency" (don't try having him throw 300 innings!). And I should cop to the fact that I'm an epidemiologist, not an orthopedist. The Mets do have the benefit of being able to look at Matt Harvey's x-rays (and talk to his doctor) and maybe after a careful analysis, it's worth capping his workload. What I can say is that as far as the "typical pitcher" goes, there is no evidence to suggest that an innings (or batters faced or pitch) limit is an effective health promotion measure for pitchers who have gone through a serious injury.

Now Pitching for the Mets…
Let Matt Harvey pitch. The data say it's okay. They don't say that he's not going to get hurt ever again. In fact, they say he's a reasonable bet to get hurt again. As a fellow human being, I hope very much that he beats the odds, but letting him pitch a few extra innings this year isn't going to be what hurts him. The damage has already been done in the fact that his UCL has been replaced.

It looks like the Mets will, in fact, let Harvey pitch. Maybe there's something to be gained from looking like they want to be a little cautious. Even if there was evidence here that limiting a post-TJ pitcher's innings did increase the risk of further injury, chances are that it wouldn't be to 100 percent. And with Harvey, the Mets have a better chance of winning a World Series in 2015. There comes a point where even if the evidence said it was a risk, you have to play the numbers on whether Harvey does more for the Mets in 2015 now that they are in the playoffs or if he does more for them in 2016 or 2017 when we have no idea what will happen.

But as it happens, it seems that it doesn't much matter. The Mets have an actual opportunity to make a playoff run. At this point, they basically have the same chance at winning a World Series as everyone else who makes the Division Series and that's a much better chance than most teams get. Matt Harvey is a really good pitcher on a team of really good pitchers. Seems a shame not to let him pitch.