A good player shows quality no matter how little time he is given.
The way he receives the ball, the way he moves with the ball, his runs on and off the ball, these are the things that differentiates a good player from a top player.
Quagliarella has minimal ball skills, even if it's more than Matri's, you'd never see him beat a player one on one or control a difficult ball very skilfully. He's very slow, probably our slowest forward equal with Bendtner. All he seems to want to do when there is half an inch of space is put his head down and shoot from anywhere, and I really mean anywhere. His runs off the ball are fairly good though, but then his lack of pace comes back to bite him anyway.
He's useful as a Coppa Italia striker, but that's as far as it goes. Vucinic should be the minimum quality that Juve have in a forward. All the Matris, Qualiarellas and Bendtners of the world are better off at a mid-table club.