The Effect of the Designated Hitter Rule on Hit Batsmen: Pitcher's Moral Hazard or the Team's Cost-Benefit Calculation?: A Comment

Since the Designated Hitter (DH) rule was introduced to the American League (AL) in 1973, American League pitchers have hit opposing batsmen more frequently than have National League (NL) pitchers. Golf, Shughart and Tollison [1997], hereafter GST, attribute this difference to moral hazard on the part of pitchers. Because American League pitchers no longer bat, they do not personally face retaliation in kind for hitting opposing batsmen, and hence "can throw at opposing batters with greater impunity" (p. 555). GST find that the introduction of the DH rule led to "a 10% to 15% increase in hit batters in the American League relative to the National League" (p. 558), and offer this increase as evidence consistent with the moral hazard story. We question whether the DH rule has really made such a large difference, and whether pitchers' moral hazard is the best explanation for whatever difference it has made. We offer a different explanation: hit batsmen should occur more frequently in the AL because, from the team's point of view, the net benefits of "plunking" a designated hitter are higher than those of plunking a pitcher. Our empirical evidence, provided below, also casts doubt on the GST result. We find the moral-hazard story questionable for the following reason. A National League team that plunked the opposing pitcher (in retaliation for his throwing at one of its players) would be putting the opposing team's weakest hitter on base, sacrificing a very likely out. A less costly form of retaliation is to plunk the opponent's best hitter, a batter far more likely to create runs for his team if pitched to normally. Retaliating against the big slugger is also likely to provide a greater benefit: threatening the opponents with injury to a top hitter should provide a greater deterrent than threatening them with injury to an average pitcher. If retaliation for a hit batsman is indeed directed at a team's big hitter, then the fact that AL pitchers no longer bat should have little (if any) effect on their willingness to hit opposing batters. We believe it is common knowledge among students of the game that plunking a big slugger is in fact the standard retaliatory strategy.(1) Of course, our a priori argument and casual empiricism are not conclusive. In our explanation, the pitcher acts as an agent of his team's manager, so there is no particular deterrent value in plunking the pitcher. But hitting the pitcher might make sense as a retaliatory second-move strategy if instead, as GST explicitly assume, the pitcher himself can decide to throw at an opposing batter. Our cost-benefit explanation for the interleague difference in hit batsmen implies that pitchers are plunked less often than are designated hitters,(2) whereas the GST moral-hazard explanation implies that pitchers who bat are objects of retaliation.(3) Support for the view that retaliation is seldom directed at pitchers is provided by James's [1987] annotated list of "significant injuries resulting from hit batsmen 1950-1984": only three of 48 cases (from regular-season games in which a pitcher batted) involved injury to a pitcher. Still, we need to take a more detailed look at the data to examine the question: when pitchers bat, is it pitchers or non-pitchers at whom retaliation is directed? Sampling of a number of years (since introduction of the DH) shows a pattern consistent with our cost-benefit argument. Designated hitters (typically good hitters, because fielding skills are not required for their job) are hit by pitches somewhat more frequently than are other batters, while pitchers (typically poor hitters, because pitching skills are much more important to their job) are hit much less frequently (see Appendix). On average, DHs in the AL have been hit at about 110% the rate of other AL batters. Since DHs get about 1/9 of AL at bats, this factor suggests that the total hit batsmen rate in the AL should exceed the rate in the NL by about 1%. …