Hitter and Catcher Adaptation in Major League Baseball.

This article focuses on advanced statistical analysis of hitter and catcher performance in Major League Baseball (MLB) using pitch trajectory data from Statcast. It introduces pitch scores that evaluate pitches based on expected outcomes independent of defensive luck, and develops corresponding hitter and catcher scores to measure skill and adaptation. Key findings include that the "times through the order" (TTO) penalty primarily results from learning by the best hitters rather than pitcher fatigue alone, that hitters incorporate guessing into their approach during at-bats, and that catcher pitch calling and framing contribute substantially more to run prevention than previously estimated. The study suggests that catcher defensive value, including pitch calling, may be worth over 11 wins per season difference between the best and worst catchers, highlighting new strategic opportunities for teams in pitcher usage and catcher evaluation.