It all depends on his wages. If the equivalent player (2/3rd choice backup) at most other prem teams demand a similar wage then it might be pointless to get rid of him. We might only replace him with a player of similar caliber and wage demands.
Trouble is, usually this kind of player is younger and has potential. I don't see anything to suggest that he'll drastically improve or push the players ahead of him to preform better. Whilst 25 isn't that old, you would have expected to have seen some sparks if usefulness by now. He'll be almost 30 when he leaves this club, his whole career for a Premier league team when imo he's a league 1/ championship starter.