With Barkley I can't help but feel that if you TRY to create 100 chances, and successfully create 40, that's 60 times attempts have failed and possession has been handed over to the opposition. It looks good because the laws of averages suggest that he will have created x amount of chances, however the amount of times he's attempted to makes those chances shows how wasteful he is in possession.
He wastes possession so much during a game, which hinders the overall effort of the team.
He has picked up form, of course, it's obvious to see, and he's doing really well. But he's still a hell of a long way from being a good number 10.