I agree that he's gone backwards in his development and not fulfilled his potential, but that doesn't necessarily mean that his career wouldn't be rekindled by a move elsewhere. There's different reasons why certain players' careers can go stale. A player that was hailed as having potential to become "England's Iniesta" must have something about him. Who knows why that potential was never realised. Maybe a move to a new club is what he needs to re-spark the flame...? (But, I concede, that the opposite could also be true!)