I think some already mentioned, but tome his position is only one: DM. I think he can become near world class at this. He's quick, tough, mobile, passes decently, can carry the ball when needed, good first touch, has stamina.
As a CM he is quite average, because the absolute lack of offensive instincts.
Just deploy the guy as a DM. I would actually think about investing him on this starting position and letting Pjanic go (he also underperforms as a regista), only to make money to get SMS - who is as real box-to-box CM.
Bentancour/Can - Ramsey/Rabiot - SMS