I agree, we have definitely made him worse. Not convinced we've given him a properly sustained run in the team, but its rare you get that nowadays if you don't hit the ground running.
Revisionism or not, he's the worst pound for pound signing we've made. Who's fault it is is sort of irrelevant, but the fact of the matter is he is a genuinely terrible footballer now.
Also - in terms of it being a good transfer... didn't we quadruple his wages? That just never ever ends well.