I don't think that is a college vs pros thing, I think it is more a group of refs thing. The biggest issue I see is the variation with the various crews. The issue is almost exclusively the subjective calls, holding (offense or defense), PI, unnecessary roughness, etc. Not every human sees it the same then fans react based on if it helps or does not help the team they root for. I agree with the let them play approach to a point....games are more fun to watch when there are not as many flags.