Because fans think paying the money to sit in those seats entitles them to be a part of the game. Fenway is the worst because the fans are so close to the field and people stock up on liquid courage during the game.
I'm starting to lose count of all the players who helped us win a WS that Red Sox fans have booed. It's pathetic and embarrassing but what can you do? There was a great caller on WEEI today talking about the new breed of fans and how clueless some of them are.
Talk radio in Boston certainly doesn't help things. Glen Ordway actually questioned whether or not it was ok for Theo to go to Pearl Jam last night, rather than stay at the game.