With regard to his potential, I seriously doubt he isn't almost as talented as Cassano, he has been among the very best players at Villareal for 2-3 seasons now in a league which is in the top 2 of the world so I doubt he doesn't have the potential to become as good as Cassano, he is still only 23.
But if you say he isn't at the level of Cassano yet, I might agree.