I agree that we need a better/faster/younger/more-consistant Fernandinho (as much as I like the guy) but it's surely not Stones. I'm only just getting used to him playing half decently as a defender in the time his played this summer. It's a huge leap to think of him actually playing in midfield.
It may be contrary to popular opinion but he isn't a good passer of the ball (IMO). You can tell by his tempo. He doesn't make quick decisions, his passes are relatively slow/imprecise and they're one dimensional, i.e. no triangles or ambition. Compare that to the likes of Garcia who's constantly looking for the ball in order to move it intelligently and his passing is crisp and snappy.
If Stones is to live up to not be a complete waste of money then I hope he proves himself to be a decent central defender and leaves the midfield to midfielders. If no one has faith in him as a defender then let him go on loan somewhere to try to improve or sell him.