because of the defense being played or the foul situation or other reasons. For example, I've coached youth sports for a long time and I typically like a really aggressive defense in basketball, but there are times where I have the team pull back and pack it in a bit for strategic purposes (e.g. the other team cannot shoot from outside).
Another situation would be if the aggression is hurting the team: e.g. a kid is trying to play pressure defense on a player who keeps beating him/her. In that situation it is better to play off and try to be more position oriented.
It just depends, but things get difficult if the coach is saying one thing and the parent is saying something else and the kid keeps looking to the stands at the parent telling them to do something different than the coach is. I agree with the above....if you want to coach, volunteer, otherwise let the coach do it.