What Effect Does Tommy John Surgery Have on the Performance of MLB Pitchers?

Tommy John surgery, which was first performed in 1974, has allowed many pitchers to come back from an injury that ended many careers. Tommy John surgery is an important topic to research in Major League Baseball (MLB), as there has been an upward trend in the number of surgeries being performed each season on pitchers. Investigating the performance and success rates of pitchers after undergoing Tommy John surgery can provide pitchers and teams a clear view of the outcomes. This paper investigates 263 pitchers from 2012 to 2022 and their success rates of return to established MLB play, as well as the performance of pitchers that successfully returned to the MLB. Using wins above replacement (WAR) and innings pitched, I have found that the MLB pitchers in this sample suffered declines in both categories measuring performance and that success rates of pitchers returning to “established” play in the MLB is 64%.