If you want to talk to them before/after, that's great. But you yelling at them to be more aggressive is just distracting to them and to everyone on the team. Sometimes, it can go against what the coach is telling them. Not only that, you're basically yelling at your kid, in front of everyone, "you aren't doing well enough."

Also, your "run faster" comment is probably my biggest coaching pet peeve. Just run faster? If only it were that easy.