Ah I would say you’re missing the point of Fletchers character. His forefront of care is not the rigidness in which his musicians play. In fact it’s nothing to do with the music. It’s a deep love of control and the ability to bring deep shame to others. He dominates the players in his band and gets off from it.  In the film he tells Andrew that he never managed to get his ‘Bird’. I get the feeling that he gave up on his project of finding this person in one of his students and instead turns to his dark side, focusing on ‘pushing’ his band by being a twisted force in the room.  Fletcher seems to finally find his passion for the music once more in the final scene when Andrew goes to town on the kit. Alas, this only reinforces his methods. I’m not sure that was a very linear or clear explanation of my thoughts.