The Designated Hitter as Moral Hazard [NYT, registration required]

In a paper presented at the Joint Mathematics Meeting in January, Bradbury, the economist, and Drinen, the mathematician, noted that the rate of hit batsmen is 15 percent higher in the American League than in the National. [...] After they controlled for pitcher quality, batter quality, game situation and other factors that also contribute to hit batters, they found that the designated-hitter rule itself "increases the likelihood that any batter will be hit during a plate appearance between 11 and 17 percent."