Isn't it Fellaini>Osman>Barkley with Naismith generally taking on the RM as backup to Mirallas and/or Coleman?
Fellaini's back up seems to be either Mirallas or Anichebe actually.
If our front 6 are:
Gibson
Osman
Pienaar Fellaini Mirallas
Jelavic
then our back up would seem to be
Neville/Hitzlsperger
Barkley/Gibson
Oviedo/Gueye Mirallas/Vic Naismith/Vic/Osman
Vic/Vellios
Barkley is the only uninjured midfielder we have who plays that Osman role. (Though Gibson has done it in front of neville) Not sitting deep the way Gibson, nev and Hitz normally do but not staying right up the way Pienaar, Felli and kev do either.
If you were going to take Osman off to rest him, he is the only like for like replacement. Which is why is strikes me as telling of Moyes opinion of him that he switched things around instead.
I honestly think Moyes just doesn't rate him as a footballer, rightly or wrongly. It's not about resting him, it's about not liking him.