Analyzing Momentum in Baseball Games Using the Leverage Index

Abstract

Does the concept of ‘flow’ exist in baseball games? Here, ‘flow’ refers to the phenomenon where a single play influences the subsequent development of the game. Several previous studies suggest that ‘flow’ in baseball is merely a cognitive bias. However, few studies have clearly defined the factors that generate or alter ‘flow’ and incorporated them into their analyses. In this study, we re-evaluate a well-known baseball adage, “opportunities arise after overcoming adversity,” using data from Japanese high school baseball tournaments. Using the Leverage Index to quantify high-pressure situations, we propose an analytical approach that considers “being right after a tough half-inning or not” as a treatment variable. Employing on-base percentages and scores as outcome variables, we examine the treatment effect through model selection and regression analyses. We also examine our results with and without the application of propensity score matching.