Batter Up! Moral Hazard and the Effects of the Designated Hitter Rule on Hit Batsmen.

American League batters have been hit by pitches 10 percent to 15 percent more frequently than National League batters since the designated hitter rule was introduced in 1973. This evidence is consistent with the idea that the American League's adoption of the designated hitter rule created a classic moral hazard problem. Because they are not required to appear at the plate, American League pitchers can throw at opposing hitters with greater impunity (i.e., at lower cost) than National League pitchers who must take their turns at bat and, hence, bear more of the costs of their own actions. Copyright 1997 by Oxford University Press.