Analysis of Pitching Metrics and Performance in Major League Baseball Pitchers Following Ulnar Collateral Ligament Reconstruction between 2010-2021

Keith Fishbeck, Conner Howard, Griffin Hughes, Elizabeth Garrett, Cameron O'Brien, Jake Checketts, Ian Rice

Research output: Contribution to conferencePosterpeer-review


Background: Major League Baseball (MLB) pitchers place substantial stress upon their throwing elbow, leading to a high incidence of ulnar collateral ligament (UCL) injuries and reconstruction procedures. Previous studies investigating pitching metrics and player performance have demonstrated varying results. Additionally, UCL reconstruction (UCL-R) has improved over recent years. Therefore, the primary goal of this study is to evaluate differences in pitching characteristics and player performance before and after UCL-R among MLB pitchers.

Methods: A publicly available list of baseball players with confirmed UCL-R was screened by to identify MLB pitchers that underwent primary UCL-R between 2010-2021. Inclusion criteria consisted of playing at least 20 MLB games in a season, within 2 seasons of surgery, before and after UCL-R. Pitchers with multiple UCL-Rs or supplemental procedures were excluded. Included players were searched on Brooks Baseball and Baseball Reference to collect pitching and performance metrics for presurgical and postsurgical seasons. Velocity (miles per hour (mph)) and pitch selection frequency (%) for fastball, curveball, changeup, and slider were collected for pitching metrics. The following performance metrics were collected: games played, earned run average, strikeouts per nine innings (K/9), opposing batting average, opposing slugging percentage, and swinging strike percentage. If data was normally distributed with similar variance, a t-test of dependent samples was used to compare differences in means. If normality of variance assumptions were violated, we used a Wilcoxon signed rank test to compare dependent samples.

Results: Based on our inclusion criteria, 80 MLB pitchers were included for analysis. Sample sizes for pitch types varied (Table 1). UCL-R was associated with a significant decrease in fastball velocity (mean difference -0.54 mph, p < 0.001, d = 0.4) and fastball frequency (mean difference -5.9%, p < 0.001, d = 0.54), with a medium effect size for both variables. Curveball velocity was also significantly decreased with a moderate effect size (median difference -0.25 mph, p = 0.028, r = 0.37). K/9 significantly decreased with a small effect size (mean difference -0.52, p = 0.024, d = 0.26) (Table 2). UCL-R had a small and nonsignificant effect on the number of games played and slider frequency.

Conclusion: This study found that MLB pitchers who underwent UCL-R and returned to play at the same level demonstrated a significant decrease in fastball and curveball velocity. These pitchers threw significantly fewer fastballs and had a significantly lower K/9. These findings should encourage pitchers to take necessary precautions to avoid overuse injury to their throwing elbow, while also providing sports medicine professionals with updated information to counsel pitchers on expectations following UCL-R. It is important to note that this study was observational, therefore, does not support causation. Additionally, the various surgical approaches, techniques, and opinions related to UCL-R and postoperative rehabilitation, which are continuously evolving, potentially influences results among various cohorts. Due to varying results from previous studies, clinical investigations focusing on surgical and rehabilitative characteristics are warranted to further establish key factors for player success and safety.
Original languageAmerican English
StatePublished - 16 Feb 2024
Oklahoma State University Center for Health Sciences Research Week 2024
- Oklahoma State University Center for Health Sciences, Tulsa, United States
Duration: 13 Feb 202417 Feb 2024


Oklahoma State University Center for Health Sciences Research Week 2024
Country/TerritoryUnited States
Internet address


  • UCL Surgery
  • UCL Repair
  • Tommy John Surgery
  • MLB
  • velocity
  • performance


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