Research Notes: The Designated Hitter, Moral Hazard, and Hit Batters

Abstract

The rate of hit batters in the American League (AL) has exceeded the National League (NL) by an average rate of 15% per season since the introduction of the designated hitter (DH) to the AL. This difference may be the result of moral hazard by AL pitchers; however, past studies have been unable to differentiate between competing explanations. Using game-level statistics from the entire 31-year history of the DH, we find the DH to be positively correlated with hit batsmen while controlling for many factors. Results indicate that the difference in hit batsmen between leagues is real and that moral hazard explains about one half of the difference. Observations from interleague play further support the notion that the results are not an artifact of unidentified league-specific factors.