You obviously never have been to an Oakland Raiders game.
I have, and there was NO violence. I was in the Black Hole, and a few seats away, there were a couple of Denver Broncos fans. They only took a few verbal jeers. This is me at the game. I think it was in '03.
Oh, and soccer is the yawniest of the yawners of sports. I think I would rather watch golf. Ugh.