When you think about it, Bernardeschi and Dybala weren’t that different when they joined Juve. They both came from a midtable Serie A team (Palermo, Fiorentina). They were both young, they both scored a double digit number of goals for their midtable club. They both cost around 40 million euros.
One of them worked out and the other didn’t.
It’s very difficult to predict the development of a young player. Kuku could become the next Dybala, or he could be the next Berna. Who knows?