Increasing the penalty is probably appropriate. Especially for the father/son duo that attacked the coach. I'm sure they got more of a penalty because they actually attacked someone. They also got a major league beat-down too.
Personally, I think the penalty for running onto the playing field is very simple. Do your best to get off of it. No arrests. A good old-fashioned a**-kicking will put an end to that kind of foolishness.