Clichy is class, no doubt, and he's been performing at Arsenal for some seasons. If I remember correctly enough, he was the best LB in the Premier two seasons ago.
That's not the case of Nasri, not at all. The ''he should play centrally'' is just the biggest excuse I have heard about him and that for years. Last time he played good at that position was at Marseille, and he clearly doesn't have the skill to play there.
People considering him as one of the most gifted players in Europe (for what? Passes: not good enough. Speed? Decent. Dribbles? Typical Ronaldo case: takes too much time and needs space. Finishing? Well, his best quality, but not quiet exceptional) really will be disappointed, let alone being at the class of Silva. May be good on the wing, but that's not at all what City needed. We needed a creative midfielder who could replace Silva to rest him, or even a JaviMartinez-like player to play more defensively in the absence of Silva.
I'm not saying Nasri won't come out good, he may be decent as a winger. Maybe. Never the 20m Silva Wannabe we were sold. Just stop making excuses like ''he would be good midfielder'', no, he won't. Nor does he need time to adapt, he comes from Arsenal and City plays a similar game to them this season.
Form is temporary, class is permanent. The 6 Nasri months were the form of his carrier, on the wing because that's where he belongs. Class is Silva, Fabregas, Ozil and Sneijder performing for years and yet sold for a similar price than that crap.
About his attitude, just search the Henry and Gallas episodes. Or when he insults fans on Twitter.