An excellent rule of thumb from Reed Maltbie, that coaches can easily implement in their next match:
Use the 100/10/1 rule to communicate during games. 100 yards is body language and hand signals, 10 yards is quick words to the entire team, 1 yard is when they are on the bench and you can have a conversation.
No more pointless yelling and joy-stick coaching from the sidelines. 🙂