I suppose finding out what is really making you angry would help. It could be it's triggering you to a similar situation or situations where things weren't "fair" for you? Or it could be a cover for sadness, such as if you were never able to play or be on a team. You could also be transferring the need/desire to not let it happen to your child, that makes it so emotional, or added to your feelings if maybe your parents didn't come to your "rescue" when things weren't made good for you?

It's worth working on... going to games and feeling great about yelling them on is fun!