This is why I hate both the Yankees and the Red Sox
Recently, fans have been getting rowdier and rowdier. I used to be one of the biggest fans of charging the court (or the field, where appropriate) at college games, but it is getting dangerous just to be at some of these games. I'm not saying the athletes are blameless; in many cases, they are just as bad. But, outside of the ocassional fight between players, these events likely could be prevented by a few things.
1) Fans who initiate such issues should be banned. Permanantly. If they can't behave at a ball game, they sacrifice the right to be there. And make this effective for the entire league; start a problem at a Cardinals game, and that person is banned from ALL Major League Baseball games.
2) When beer is sold, limit how much someone there can buy. This could be done simply by marking the ticket stub each fan comes in with.
3) Put a buffer zone around the field/court. I know this reduces room in many already overcrowded stadiums, but perhaps five feet of seperation might make it a little more difficult for confrontations (this is more aimed towards the Sheffield incident, it might not have helped in the other two situations unfortunately).
Unfortunately, this issue is impossible to completely control, but new stadium rules may be able to deter such atrocious behavior.
Sigh, I miss being able to rush the field. Thank you, rowdy fans, for taking that away from me.