Designated Hitter Rule Debate: A Search for Mr. Hyde in Pitchers

Abstract

This article investigates the effect of baseball’s designated hitter rule on the number of hit batsmen, with a focus on individual pitchers. Researchers have debated the rule’s incentives for pitchers and its impact on hit batsmen based on aggregate and cross-section statistics: They treat pitchers as a group. This article argues that individual pitchers are concerned with their reputation in the baseball community, and that they do not necessarily respond to the rule change by throwing at batters. Analyses of performance data of individual pitchers in a Japanese baseball league indicate that the rule did not prompt their behavioral change.