Let's look at 2013:
Stoke 3-0, Kompany, Lescott - Clean sheet
Watford 2-0, Kompany, Lescott - Clean sheet
Arsenal 2-0, Kompany, Nastasic - Clean Sheet
Fulham 2-0, Kompany, Nastasic - Clean Sheet
Stoke 1-0, Kompany (Injured 39th min), Lescott - Clean Sheet
So now Kompany is out, end of January.
QPR 0-0, Lescott, Garcia (Nastasic benched) - Clean Sheet
Liverpool 2-2, Nastasic (Subbed 55th), Lescott
Southampton 1-3, Garcia, Lescott (Subbed 65th), Kolo benched and unused
Leeds 4-0, Kolo, Nastasic (Lescott benched) - Clean sheet
Chelsea 2-0, Nastasic, Kolo (Lescott benched) - Clean sheet
Villa 1-0, Kolo, Nastasic (Lescott benched) - Clean sheet
Barnsley 5-0, Lescott, Kolo (Nastasic benched) - Clean sheet
Looking at this, City had cover on the bench on basically every match when Kompany was out. And the only real let down to me performance wise defensively is Southampton, Liverpool is a good team.
So why the hell is Mancini opening his mouth? What is there to gain from saying this? Just keep quiet, why telling the world that you're not satisfied with your current players. Maybe City could've used another defender in one instance but how many teams in the world can afford to have 5 class CBs? Not mentioning that Rodwell, Garcia and Yaya are capable as CBs, while Kolarov also played there in Lazio.
When you've had 10 clean sheets in 12 matches and saying things like that... I don't get it.