Dick Richards of Come Gather Round gives an example of why he suggests Don't Shield Them From Distress: An Example and closes with a great comment:
... don't expect that telling the truth alone will be enough to initiate change: expect instead that witholding distressing truths may render change impossible.
Interesting. If you don't provide people with your assessment, then they will never know how you truly view their contributions. And without that information, how can they possibly know whether they are moving in the right direction or the wrong direction?