hi there, a couple of suggestions:
- make it simple and do not worry or over-think about it. it happens
- what are the key measurements of performance? regardless of your feeling or other's comment, objectively, this person is doing well, OK or really lousily ?
- be specific. it might be the case that this person is good at certain things, not that skillfull or thoughtful on some othere. please make it very clear on what he is good, what he needs to improve
- in case possible, try to join his meetings/projects to get first handed info.
