I think coaching your team members privately and regularly is the most important way to improve the performance of each individual and the team as a whole. There are many posts on my blog explaining how to coach.
There are, however, many situations where coaching is not going to work:
1) When the person does not care and you know that they never will
This is where you are trying to “save the un-saveable”.
2) When the organization is on a witch hunt (right or wrong) and you both know you are just going through the motions.
If the result is a foregone conclusion, how are you supposed to coach in a caring way and how is the person supposed to buy-in? If this is the situation, you are undermining your own credibility. Don’t do it. Be humane and do what you both know is going to happen anyway.
3) When there is an intellectual or technical issue.
Coaching is about changing behavior, not teaching basic technical skills or trying to improve someone’s core intellect. You will fail at this and you will do far more harm than good to the person on the other end of your efforts.
4) When the person is fundamentally unethical or lacks integrity.
If you become aware that someone truly lacks integrity, fire them and don’t try to coach them.
The good news is that 70% of the time you will see great results from following the coaching process. Issues with a particular employee can be substantially improved by coaching them with a focus on behaviour. The other good news is that proper behavioural coaching almost always works as long as none of the issues I have just explained are present. The key thing then is to recognize when coaching is going to fail and dealing with the situation in a far different way.
Thanks to Marshal Goldsmith for putting this into perspective for me. He explains it far better than I in this short video.