Maybe wording ..
He isn't a position player, e.g. he won't work in a (as example) Conte side where you are expected to be with 1 yard of x position with/without ball, I'd put him the same as Rafa VDV, not they don't work hard but they need to play to their instincts
Like I said, see what Pep has done with Grealish, some players don't work in rigid systems, the issue is more and more, teams play rigid systems/expectations.
Really not qualified to make the point, sometimes you want to do something, sometimes you believe you have to do something, but you can't quite? (if that makes sense). At this level, you have to be able to physically do it, mentally do it (focus/commit/buy in) and be given the appropriate opportunities
I think for him, none of those things are 100% where it needs to be. And unfortunately I don't see a way home/back for him, hopefully I'm proven completely wrong and he gets a swansong few years ..