He was a sensation at Ajax and is a total and utter flop at Chelsea. Not sure how anyone can be definitive at where he is now performance-wise.
His shitness, and let's not try to make out he has been anything other than shit at Chelsea, might well be down to profile and fit both with Manager and Player etc. I think he at least did enough at Ajax to demonstrate that within that team's style and set-up his profile was perfect.
But does beg the question of whether (assuming the links are genuine) how the fuck his profile would be a good fit in Conte's system. If we played like Ten Hag's Ajax then we should be all over him, but we don't, not even remotely close.