I think if a coach has to yell, they obviously failed to cover something prior, but think yelling and placing the blame on the player is somehow constructive. My son is 11, and I like the way his football coach does things. He will yell to motivate and congratulate players, but won't yell across the field at a player. He will take them aside and talk to them if they f'd up, but not openly call them out in front of parents and players.