VARIATIONS IN PITCHING PERFORMANCE DURING A MAJOR LEAGUE BASEBALL GAME: WHAT CAN WE LEARN FROM BALL TRACKING DATA?

Abstract

The aim of this study was to identify changes in pitching characteristics during nine innings of professional (MLB) baseball. Ball tracking data were obtained for 1,514,304 pitches thrown by 129 pitchers during the 2008–2014 MLB seasons and compared across the nine innings using linear mixed model analyses. Earlier innings contained significantly more hard (i.e., fast-type) pitches. A significant decrease in pitch speed and release height emerged before the sixth inning. These data revealed that aspects of a starting pitcher’s performance significantly change as early as the second or third inning of an MLB game, although these do not influence his effectiveness. Coaches may use these data to inform their decision to relieve a starting pitcher and/or direct in-game strategies to exploit trends in pitcher performance.