If the Nasri news is real, I'd say it's more about his continuing to openly run his mouth off about Arsenal than his performance. He played better in the second half of the season -- certainly well enough to not decide to sell him after 1 season.
I am sure Khaldoon and Sheikh Mansour don't appreciate Nasri's spouting off because it goes against the team persona they're cultivating. They do a lot to make sure City looks good in the press. Mancini may talk about other players and Mario may do stupid shit, but they don't talk shit about other players or teams.