One thing that happens because of Silva and happened a couple mins back there, Liverpool player runs into the defender, ball comes loose, it gets cleared to about 20 yards outside their own box and no one is there because Fernandinho was almost in line with the back four, Yaya was 5-10 yards out and Silva/Nasri rarely get back quickly enough. Any other team you'd have a fast winger get back and be ready to go and get those balls then start the counter but with Nasri/Silva you often have those two barely walking back, Silva was over the half way line walking towards his own box and unable to go and win it.
Both lack of pace and lack of workrate in those situations cost City loads of potential counter attacks. If he picked up the ball there he turns and you have the ball in behind for Aguero situation with most of Liverpool players in the City half, instead it becomes another attack. Even when they do counter again it's one player with the wingers who on any other team would burst up to support, here, they just aren't fast enough to support.
EDIT:- When they had Tevez, or even Bellamy, those types of players playing those wide roles they were a much stronger more rounded and more consistent looking team.