Causes of Variation in Swing Adaptation to Pitch Location

Ascertain the reasons for inter-batter variation in swing adaptation to pitch location, where adaptation is defined as the co-variation of bat speed and swing length with pitch location, and explain why different batters display differing adaptation patterns.

Background

The authors model intended bat speed and swing length using Bayesian hierarchical skew-normal models, capturing batter-specific random slopes with respect to pitch location (horizontal and vertical). They observe substantial between-batter differences in how swing metrics adapt to pitch location.

Despite documenting this variation, the mechanism underlying why batters differ in adaptation remains unresolved. The paper explicitly leaves understanding these causes for future work and suggests that additional swing path measurements (e.g., tilt and attack angle) released by MLB in 2025 may aid investigation.