One of the reasons why I think Pedro's being jumped on is that Zim is 72 and has a metal plate in his head. I think both parties were at fault in this, but to some, it just doesn't look cool when a 32-year-old guy makes contact with a guy 40 years his senior.
Plus, Pedro was considered a massive headhunter back when he was pitching in the National League. Some people suggested that perhaps he would temper his style if he were forced to bat and face the consequences of his actions, but I kind of doubt that.
