Pitch-Tracking Risk Factors and Warning Signs for Ulnar Collateral Ligament Injuries in Major League Baseball Pitchers

This study identified distinct patterns of mechanical variability and short-term changes in fastball pitch-tracking metrics among MLB pitchers who ultimately underwent UCL surgery. Greater intra-outing variability in fastball velocity and horizontal release position emerged as potential risk factors, suggesting that less repeatable mechanics may be linked to injury. A cascade of warning signs also appeared across time points, including shifts in horizontal release point and fluctuations in extension variability which intensified before injured list placement, increased spin rate throughout the season, and a progressive decline in velocity in the final outings. By focusing on intra-pitcher variability within matched time windows, this analysis isolates short-term deviations from each pitcher's baseline. As pitch-tracking technologies advance, frameworks that benchmark a pitcher's current mechanics against their historical variability may enable earlier detection, workload adjustments, and injury prevention.