During his last season he was a little inconsistent yes. That could be due to a thousand and one things. A move was mooted, he had mixed feelings or apprehension. A falling out with a team mate(s) due to a potential move or something else. An argument with his partner, absolutely anything. It happens with all players, all teams, all sports. Which you'll probably agree with.
What I would refer too, perhaps others too, are comments, perhaps not from you but others, like, "we can do better", "he clearly doesn't want to be here", "he's past his best", "he's not the goalie he was". All comments a little harsh and inaccurate. Form is temporary. We hate to see good players leave but it happens. We should all thank him for his time here and wish him future success. Snarley comments, in my opinion, are totally unwarranted.