He's of no use to a big team anymore for various reasons.
His lack of vision and inability to play a ball at first touch make him a below average AMC. When he was faster, his great shot made him an ok AM, but being this slow he's done as an AM considering he lacks the vision and passing.
Pirlo spent a career playing as a deep lying playmaker. His lack of speed was easily compensated by his smart movement, vision and incredible passing ability. Hernanes never played it before and you can't learn to play this role so late in your career, especially if you're this slow and can't play long balls or pass with your first touch. You're only a defensive liability.
Perhaps we are too harsh on Hernanes, because he can't play this, just like you can't play Chiellini as a CM. But the simple fact is that he can't play this role and he has no place in Juventus elsewhere.