We strengthen the client's skills rather than help them beat the other team. A best friend is wonderful to have. It is more rewarding to have a best friend and a coach. They want to learn and grow. It is as simple as that.
Coaches help a client get all three.
Efficiently and effectively. You take more effective and focused actions immediately. You stop tolerating what is dragging you down. You create momentum so it is easier to get results. You set better goals that you might not have without the coach.