He did well with Napoli, and if we were talking about ability only, i'd take him over the likes of Inzaghi any day of the week, but for me personality DOES matter. As Juve coach you should have a certain amount of class, and knowing AA, he's concerned about his public image as well, that's why i can't imagine us signing him.
Btw. Although i think he did well, i feel like people talk down the squad he's had at Napoli. Imo He didn't make them overperform all that much, it simply was a very good squad as well, hands down the 2nd best in the league.