Entertainingly enough, I've heard from a reliable, first-hand source that hockey players are actually really nice compared to other athletes of other sports.
Try telling that to the Pittsburgh Penguins and the Philadelphia Flyers. Just sayin....
That's the rivalry that happens when you let s state go and have 2 competing teams. Pennsylvania learned from this and thus only has one NFL team (All of Pennsylvania is "Steeler Nation").
I expect that when you're in a sport where you wear armor and razor blades and can arbitrarily beat your opponents till they bleed, with practically no penalty, that you could be pretty laid back as you get a great outlet for anger.
Interestingly, despite steroids and all the strength training, football and baseball have the worst fights.