He's not being used right, in my opinion. He should never be the last midfielder back at any time because he isn't as press resistant against the top level teams/traps. He is technically good enough for a one touch pass it off and move type situation, which is what he does for the Spanish national team.
He's a great squad option, but Arteta relies on him as a first teamer because he suits control ball ethos (press, physical, aerial prowess, duel winner).