He's probably right - whether the fans boo or don't boo likely doesn't affect the outcome of the game. We would like to believe that our booing would inspire the players to be better, but that's probably delusional.
Is he really wrong that teams go through slumps (sometimes longer than three games) and that good teams work their way out of them?
Is he really wrong that the puck isn't going in for him (or the people he sets up) at the moment? If he continues to generate chances for himself and teammates, there's good reason to believe they will return to normal.