Philadelphia sports fans in general are just pricks, and they fully embrace it. I thought Red Sox fans were nasty, they got nothing on Philly fans. I went to a Flyers-Penguins game with my roommate freshman year and I saw three middle-aged Flyers fans ruthlessly pick on an 8 year old for wearing a Crosby jersey.
I think this fits the attitudes of Philly in general. Despite being the fourth biggest city in the US, they are considered "not important" and "lesser" then the other three major East Coast cities. This feeling of inferiority carries over to sports and they become obnoxious and abrasive to make up for their feeling of inferiority.