I see nothing wrong adding a player to the midfield on a free transfer. Now would I pay him 5 million Euro to play one-third of the games? No. If he comes, he also will have to take a reduction in wages.
I also don't necessarily believe he wouldn't play more. Pogba and Pirlo might not be here and we don't know if Juve will pay the transfer fee for Pererya to become a full member of our club. That leaves Juve with Marchisio, Vidal (who is always rumored to be going elsewhere), Asamoah, Sturaro, Padoin and Marrone in the midfield.
I think right now the midfield is most in flux because I believe Tevez will be back and Morata definitely will return. The strikers are just missing a 4th option if Dybala is a definite to come. And on defense I think we are solid with Chiello, Bonucci, Evra, Licht, Barzagli, Ogbonna and Rugani if he arrives from Empoli.