What I know is, him at 10 doesn't improve our play. We might as well have kept Mata for that. What he can offer us is that build up and ball retention from a deeper role, a la Alonso. His defensive problems are up to Mou to cover, like by having Willian or Oscar act like a 3rd midfielder when we're not in possession. Whatever the case, we can't play 2 defensive midfielders like Rammy and Matic, then expect them to start attacks against defensive teams.