I disagree, I think he’s appropriately rated. I haven’t seen anyone bigging him up to be this world star like people used to do with Barkley comparing him to Lampard and Gerrard.
He showed a lot of improvement, but can improve a lot more if his development keeps going in the right direction. That's why selling at this point of his development should only be if something crazy was offered. You shouldn't sell players way before they maximise their potential value.