Mancini has talked about wanting two top class players for every position. I think by the time Milner and Balotelli have signed, we won't be too far away from that. One position I do still feel we're short in though is RB. Boateng has arrived and most fancy he will be used mainly as a right back, although he supposedly prefers to play in the middle. Other than him, we have Micah who for three years has had potential but not lived up to it, Onuoha who appears to be on the way out and Zabaleta who has never let anyone down but a top class RB? I'm not so sure.
With Kolarov known to be keen to get forward, I think if Mancini could convince a right sided version (Maicon/Alves?) to come, he would be able to play the extra defensive midfielder, as he likes to do, and the threat offered by our full-backs would more than make up for it.
I think Milner will prove to be a good signing but if Mancini wants these two top class players per position, I think he should be looking for a new right back before any more midfielders.