I often hear people say Nasri can't play good enough here because he's in the shadows of Silva, but that's actually just an excuse Nasri fans have been putting up for two years now.
Truth is that, even when he played at little clubs like Marseille and Arsenal, he never really got the midfield playmaker role for the simple reason than he doesn't have the vista to play at that position, nor does he have the technical ability. If I remember correctly, he only had 2 assists at Arsenal and, with us, he mostly only gave Corners/non-key passes transformed into goal.
As for putting him on the wing, sure it worked at Arsenal, or at DM for Marseille, because he could do a nice fancy action once every 10 match with a one two or some Quaresma type dribble, but that doesn't work at City because we are champions and we need wingers far above nasri's level.
Even if you look at his last season end, you can see how inconsistent and how dependant on Silva/Tevez he was, he won't ever make anyone play better like Silva does.
To me, he just isn't City Material, which Isco may be.