Maybe his coaches never changed their strategy and techniques for him to adjust to his age, schedule and damage. I think if you look around the UFC roster you will find a lot of fighters that could most likely benefit from a change in gym, fight camps or fight trainers. I think you can only get so good doing the same things with the same people, it may sound stupid but as a Chef staying in the same kitchen for 10 years is extremely limiting to your skill set, I've found it's best to move around every few years to pick up new skills and put old ones back in to use. I imagine it would be similar in professional fighting and a lot of other things.