In order to win the Champions League you need a good defence as well as a good attack. City only have one of the two when Vincent Kompany is injured.
Even when the captain is in the side the defence is not amongst the best in Europe. Without him there is no way City is going all the way in the competition.
Unfortunately for the club, Kompany is quite injury-prone and it is simply baffling City did not try harder to buy a centre-back in the summer.
Matija Nastasic, Joleon Lescott and Martin Demichelis are not the same class.