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Tommy John Surgery in Major League Baseball

September 14, 2018
 This month, two of baseball’s promising young pitchers—Shohei Ohtani of the Angels and Michael Kopech of the White Sox—learned that they will likely need Tommy John surgery due to torn ulnar collateral ligaments in their throwing arms. While Ohtani remains in the Angels’ lineup as a hitter, Kopech’s debut season is over after fewer than 15 innings. 

In the 2018 Bill James Handbook, Sports Info Solutions added Tommy John surgery information for every pitcher who appeared in MLB in 2017, including surgery dates. This information will be updated for every 2018 pitcher in the upcoming 2019 Bill James Handbook as well. Did you know that several pitchers have undergone multiple Tommy John surgeries? For example, Oakland A’s reliever Shawn Kelley has had two surgeries—the first in 2003 and the second in 2010. 

More than 25 percent of the league’s pitchers in 2018 have undergone Tommy John surgery at some point in time. That’s a surprisingly high figure, demonstrating how common the procedure is, as well as how pitchers have been successfully able to pitch in the majors after the surgery. 

Over the past three years, just under 20 additional MLB pitchers per year have had the surgery. There are also typically about one to three Tommy John procedures for MLB position players each season, such as the Dodgers’ Corey Seager and the Mets’ Travis d’Arnaud in 2018. 


Among the pitchers who have returned to the Major League level after the surgery, the average return time is about 19 months, while the median is 16 months. Long recovery times skew these results; the most common returns are 12 and 13 months. 

However, not every pitcher returns from the operation—for example, former relievers Joel Hanrahan and Joel Zumaya. More than 20 percent of MLB pitchers who had Tommy John in 2016 or earlier did not return to the majors after the surgery. 

We also looked at how velocity changes after Tommy John surgery compared to before, considering fastballs thrown one year prior to the surgery date and one year following the return date for pitchers who returned to the same role (starter or reliever). 

Of the 156 pitchers in our sample, 96 had a lower average fastball velocity in the year after their return. The median increase among velocity gainers was about 0.6 miles per hour, while the median decrease among decliners was about 1 mile per hour. The declines may not be entirely attributable to the surgery, of course; pitchers tend to lose velocity steadily with age

That said, players who are younger at the time of surgery are more likely to gain velocity when they return. Of the 94 players who were 28 years old or younger, 43 saw their velocity increase (46 percent). Of the 62 players who were older than 28, 17 saw their velocity increase (27 percent). 

Baseball researcher Jon Roegele's publicly-shared Tommy John Surgery List is an invaluable resource that aids Sports Info Solutions in the collection of Tommy John data. 

COMMENTS (5 Comments, most recent shown first)

Ouch! Don't have Tommy John surgery if your name is Joel!

This study is long overdue. It shows that something is very wrong with the way we train and use pitchers in modern baseball. Pitchers need to learn how to pace themselves, and pitch to contact. This business of "throwing as hard as you can for as long as you can" puts too much strain on the arm.

The endless matchup games that modern managers play limits the number of useful innings that relief pitchers can pitch. A reliever can throw 30 pitches warming up, only to come into a game and make 4-5 real pitches, and then he does it again tomorrow.

The number of innings pitched goes down, the number of pitchers on a roster continues to grow, and more strikeouts are recorded. But is it better baseball?​
7:20 PM Sep 17th
Interesting.. I never would have guessed 25 percent.
4:38 PM Sep 16th
Does this chart or any of the data include pitchers in the minors? If not, it should.
3:13 PM Sep 15th
Sort of a Cliff's Notes on my comment:

It seems to be assumed 'out there' that if a pitcher has TJ surgery he'll be basically fine, after the recovery period.
I think there also does seem to be an assumption that the main fly in the ointment about it would be loss of velocity.

I don't know that either thing has been shown to be worthy of assumption, and in fact I doubt that either thing is true. A study like the one in this article could be a start toward answering much of that, maybe all of it.
8:16 PM Sep 14th
.....I thought you would also have given some findings on how good they were after surgery compared to before.

And then, taking it further, someone (I know that this further kind of thing isn't usually part of what you do in these) ....someone could take that data and, as a "control," compare it to the future effectiveness of comparable pitchers who didn't need or have such surgery.

Just looking at velocity is nice, but IMO it isn't much, especially since -- as you say -- pitchers typically lose velocity with age. (We really need a 'control' for the velocity change too.)

But the main thing is, nothing about how good they were after the surgery, compared to before. That's at least a mild disappointment.

So, this is just a bare beginning at most, unless there's an assumption that velocity change tells the whole story, which I doubt it does. If there's such an assumption and if this assumption is valid, then this is still just a beginning, but not a bare beginning. :-)
8:12 PM Sep 14th
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