I have been at many a national league games where the headhunting pitcher got pluncked himself (usually in the back). I take that as a first warning. The headhunting pitcher typically gets the message. The next time it will be at YOUR head. Behavior modification can be readily observed. Has anyone ever looked at the data of a pitcher hit by a pitch and their subsequent throwing behavior? The Mahoney hypothesis is that hitting the other team’s batters goes down MORE than if the pticher’s teammate gets hit.

By the way, another type of moral hazard is that a pticher can get better stats through intimidation in the American League. Sure it might cost the star teammate getting hit, and the team losing more games with that player injured. But hey, the piticher’s stats will be better through intimidation, and he will get a better salary next year. Fire away!