Background: In 2023, Major League Baseball (MLB) implemented a pitch clock (PC) to reduce game duration. Concerns have emerged regarding its effect on injury rates, particularly ulnar collateral ligament (UCL) tears, by reducing recovery time between pitches.
Purpose: To assess the correlation between the MLB PC and UCL injury.
Study design: Cohort study; Level of evidence, 3.
Methods: UCL tear incidence was compared between pre-PC (PPC) (2021-2022) and PC (2023-2024) eras. Data on UCL injuries were collected from publicly available databases. Variables collected included player demographics, advanced pitching metrics, total pitches, innings pitched, and games played. The primary outcome was UCL tear incidence per 1000 innings pitched. Secondary outcomes included UCL tears per innings pitched in the season of injury (preinjury workload innings [PIWi]) and UCL tears per pitches thrown in the season of injury (preinjury workload pitches [PIWp]), pitch count per season, fastball velocity, and pitch selection.
Results: There was no significant difference in UCL tear incidence between PPC (0.63) and PC (0.67) eras (P = .73). However, PIWp was significantly higher in the PC era (n = 721) compared with the PPC era (n = 442) (P = .009), and PIWi was significantly higher in the PC (45.7) era compared with the PPC era (26.5) (P = .003). Pitchers in the PC group were significantly younger (28.4 vs 31.0) (P = .0002), threw more pitches per season (710 vs 441) (P = .02), and averaged more pitches per game (54.9 vs 35.5) (P = .0005).
Conclusion: The PC had no observed effect on overall UCL tear incidence but was associated with a higher preinjury workload. These findings challenge fatigue-related injury theories and suggest potential protective effects of the PC.
Keywords: Tommy John; UCL; UCL reconstruction; baseball; pitch clock; pitching.
© The Author(s) 2025.