Juve sold a half share in the attacker to Parma last summer for 3.75m, but bought him back earlier this month for 11m.
"I hope that he can find some consistency in Turin," the former Azzurri boss told Sky Sport Italia on Wednesday.
"It is clear that no player can be assured of a first team shirt, he must therefore show what he can do when called upon.
"Giovinco has grown up a lot, but he can still improve. He will become an extraordinary player."