Vidal has the potential to be a perfect midfielder, or rather 'had' consider his age. He's always had it. When Juve bought him, I told you guys that he had the potential to be a WC player and back then no one here even knew who he was.
But for lack of focus, lack of self-discipline or whatever, he never fully and truly lived up to that potential. He shows flashes of it now and then, but for the most part he has remained a broken promise.
Yes, he is still a very good player but he achieves that by coasting on his natural talent and potential, which I guess only makes one wonder what he could have become, if he had had the focus, discipline and determination necessary to turn all that potential of his into actual product.
Vidal had the potential to be a great player, a legend even. He had the potential to be better than say Nedved, to put in Juventini lingo. But when all is said and done, I don't think he would have reached the heights of even an Emerson or a Gilberto Silva because those two, while not as naturally talented as Vidal, were more consistent and reliable back in their heyday.
In the end, Vidal will be a player of "local" importance, 'local' as in limited to Juventini. Nothing more than that.