Simply rewrite the rules about injuries. If determined that a player deliberately tried to injure another player, they are ejected for the same time that the injured player misses and that team does not get to fill that roster spot. So if a Cueto deliberately kicks a Larue in the head during a brawl, his career is OVER. If a pitcher is determined to have hit a batter in the head deliberately or a player sliding into Second trying to hurt another player, the team as a whole pays the penalty. There is a huge difference between breaking up a double play cleanly and trying to hurt another player.