Pitch Counts and Injury Incidence in Major League Baseball: Responses to Pitch Clocks and Defender Rule Changes

Background: The implementation of the Major League Baseball (MLB) pitch clock in 2023 aimed to shorten game durations and enhance pace of play. However, concerns have been raised regarding its potential effect on pitcher health, particularly related to musculoskeletal and elbow-specific injuries. Purpose: To determine if recent MLB pitch clock rule changes have affected total pitch counts, time to first injury, total injury time, pitches per inning, total batters faced, or total musculoskeletal injuries for the 200 highest-volume pitchers across 2 full seasons postimplementation (2023 and 2024) as compared with 2 seasons before the change (2021 and 2022). Study Design: Descriptive epidemiology study. Methods: Pitching and injury data were collected from the MLB official website for the 2021-2024 seasons. A total of 800 high-volume pitcher-specific seasons were evaluated, representing 290 individual pitchers over the 4 seasons. The 200 highest-volume pitchers by pitch count per season were included. Outcomes included total pitches, batters faced, time to first injury, total injuries, and injury type. Statistical comparisons were made between the preimplementation (2021–2022) and postimplementation (2023–2024) periods via t tests, chi-square tests, and Cox proportional hazards modeling. An injury was defined as a musculoskeletal injury resulting in a player being placed on the injured list or missing at least 15 consecutive days of game time. Results: The total number of injuries decreased significantly, from 50.4% in the preimplementation period to 39.3% in the postimplementation period ( P = .003), and mean time to first injury increased from 142.8 days to 160.9 days ( P < .001). While the number of batters faced rose significantly from 525 to 575 ( P < .001), total pitches and pitches per inning remained stable. Although elbow injuries increased in 2024 after declining in 2022 and 2023, the overall rate did not significantly differ from 2021 to 2022. Conclusion: The current study shows that after the implementation of the MLB pitch clock, injury rates among high-volume pitchers decreased and time to first injury increased, with no significant rise in elbow injuries. These findings suggest that the pitch clock has not increased short-term injury risk, although ongoing research is needed to assess its long-term effects.