At SD earlier this week, I led a tutorial about coaching. Imagine my surprise when I asked people why they were there, and some of them said, “I have a person who's not doing so well. I need to coach them.”
Uh, no. You need to give that person feedback. Feedback is information about the past, given in the present, with the goal of influencing the future. (That's a paraphrase of What Did You Say?.) Coaching is helping people see other options, and therefor helping them increase their capacity or capability.
Feedback is something managers must do. The more collaborative the team, the more everyone on the team needs to know who to give and receive feedback. But coaching? Coaching is optional.
People choose when they want coaching. They choose their coach. It's not acceptable to impose coaching on someone else. (Esther and I showed examples of this in Behind Closed Doors: Secrets of Great Management.)
If you're a manager, make sure you know the difference between coaching and feedback. Otherwise you'll confuse your team members, spend too much time with the people who provide the least value, and not coach the people who could use your coaching.