I don't think Demien is in shape often enough. I don't blame him, nobody wants to stay in camp all the time, especially going into your forties. I'm sure he lives an active life, but he's never been a great athlete.
Taking short notice fights is brave and kind, but they are not doing him any favors if he can't be excellent in the off season. His cardio, energy and attack all suffer. Think of him as a BJ Penn. An inability to maintain annual discipline, an inability to win after facing adversity.
He may be the greatest grappler alive, but who cares if he can't implement it against the top fighters? At this point you can keep him and he may do well against lower ranked fighters, but what's the point if his title aspirations continue to dim?