They need somebody who will push them and get them to step up their own game, not a friend. Parents should be the influence and teach them life lessons on how to be(come) a man. There are some cases where a role model/fatherly figure might be better, but outside of some select circumstances the first coach is always the better option. The jerk coach is even more necessary for a talented player, keeping them in line and showing them they're no better than the rest of the team. Might be a jerk, but they don't need to have a relationship once he graduates