Wenger knows how to play his cards right, but Cazorla was a different situation altogether, and that comment about not knowing who he was was obviously tongue-in-cheek.
The only sources regarding Dybala by contrast are coming from Palermo, who have a known history of drumming up interest for players through the press. Zamparini has put into system to buy highly rated south american talents and then sell them as soon as they begin to look like decent players.