Jose can be a part of a lockdown defense. He knows what to do. He knows where to be. He doesn't make horrendous mistakes, he just gets beaten by speed, and much less so when he's not hampered by injury. He used to give up on defensive plays far too easily, and now he hangs in there and fights when a faster guy is going past him. That makes a huge difference in terms of team defense. You can't tell me that Fisher plays any differently.
The guy doesn't need a special situation to make up for a gigantic weakness anymore. He's worked on his defense to the point where it is not the albatross so many are still seeing somehow. He would do well on any number of teams. But he is going to excel as a backup, because then he doesn't have to tax his body as much.