He has the workrate and creativity to play in midfield.
From what I have seen of him, I agree if 4-3-3 is the way Max goes. I have felt the same with Cuads being given a try in the backline. Both MF and RB appear to need help in getting Juve to be the best it can be.
Might seem unconventional but going further I imagine these 11 being the squad that would produce the best results for Juve down the road ..... say CL's knockout stage.
Buffon
Cuads - Rugani - Chielinni - Sandro
Berna - Pjanic - Matuidi
Dybala - Higgy - Costa/Mario
Mario playing so well now (his tank probably will never hit empty) probably would be better than Costa though. Also don't think it will happen but if Benatia continues with his form hard to bench him. And leaving my boy CM8 out hurts but looking at the 11, Matuidi gives the team more balance.