I honestly didn’t know the answer, but assumed the rate was rather low.
I grabbed data on Tommy John surgeries from Jon Roegele’s indispensable database and draft information from Baseball-Reference. I focused on drafts that have occurred since 1986 and just the first 10 rounds. I then isolated individuals drafted as pitchers and merged the two data sets based on player name.
The overall rate of teams selecting pitchers who have already undergone Tommy John surgery appears to be 1.8%. Now, that rate changes a bit over time. There are many reasons for this, I’m sure: increased prevalence of the surgery, teams becoming more comfortable selecting a player who has undergone the surgery, and simply better data in the Tommy John database for later years.
In any case, here’s the rate trend by year:
Starting in 2006, the rate begins to increase, with the highest rates coming the past three seasons. On average, teams are now selecting pitchers with a prior Tommy John surgery between 7-9% of the time.
Who’s getting selected and by whom also differs to some extent.
If we cut up the data by the type of school out of which the pitchers are being drafted, teams are selecting Tommy John pitchers from four-year colleges and junior-college programs at a higher rate than high school. Since 2006, the rates are 5.5%, 5.1%, and 1.8%, respectively.
In terms of teams, it varies quite a bit. Here are rates by team, by year, since 2006:
The Astros and Mariners have completely stayed away from drafting pitchers with prior Tommy John surgeries, while the Brewers, Cardinals, Nationals, Padres, Rangers, and Reds have all seemed to become more comfortable with selecting these pitchers.
Note of caution: the matching was done quickly and without player IDs, so there may be a few errors here and there. Also, since the database I pulled the surgery information from is based on media reports the dates of surgeries are not exact in some cases, so user beware.
Bill leads Predictive Modeling and Data Science consulting at Gallup. In his free time, he writes for The Hardball Times, speaks about baseball research and analytics, has consulted for a Major League Baseball team, and has appeared on MLB Network's Clubhouse Confidential as well as several MLB-produced documentaries. He is also the creator of the baseballr package for the R programming language. Along with Jeff Zimmerman, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Twitter @BillPetti.