The Principal Flute that I studied with had serious issues. When they began to appear in performance and, even worse, in recordings, the axe started to fall. At the time, my position was to be supportive of the Principal, rather than considering the effect on the rest of the orchestra. I even called the Director (as did others) to ask that this person be allowed to keep their job. They were fired later, anyway.
In hindsight, I think that was a mistake. So the suggestion might be that those who have contact with the player, as colleagues, or even students, be as honest as they can and at least ask some good questions, if they dare.
Le Chant du Rossignol...(song of the nightingale) 