I think rotation's entirely feasible without upsetting too many player...
Tevez/Aguero/Dzeko (2 of 3) can be rotated fairly well. Balotelli MUST take 4th place I'm afraid. I'd almost be tempted to sell him, and have Guidetti as 4th.
Silva / Nasri can be rotated, or played together if we're going for more attack.
Garcia / Toure / Barry / Milner / Rodwell / Sinclair is the problem area, that's a lot to try and rotate, esp when Toure is virtually nailed on the team sheet. Mancini probably wants to phase out Barry due to age, but is caught in the catch 22 situation of 'every game is difficult' - and needing Barry but wanting to give Rodwell a run out. Sinclair's going to struggle to get a game, and Garcia / Milner are smilarly tenacious, but possibly Milner's a bit quicker and able to go forward more.
But still, rotation's the name of the game these days - so we just have to manage it sensibly, and largely I think Mancini's doing that.
I feel we're a fragile team at the moment. Comeback kings is not the reputation we want, and unlikely to work against top class opposition. Fans are anxious too, as we want to do well in Europe, and we've gotten a tad complacent about winning games. Generally speaking, we're not getting battered in Europe, but we are losing. 'Not quite good enough' is a fair appraisal I'd say. But it would also be fair to say "not far off". We probably failed to bring in two very high quality players in the summer and that's showing. But it's too early to say Garcia's not good enough - he needs more games.
Mancini's still the man for me (at the moment), and if he can accept we don't have 50 million to spend, but he CAN sell to buy, then selling Balo for 20 million, and possibly Dzeko for 20 million too, would net him 40 million. That's enough for (say) Cavani.
He could do the same in midfield, selling 2 or 3 average players to bring in 1 top class, or maybe 2 (if he was given additional funds).