Yeah Drogba arguably should have started for his holdup play but I think the plan was to hit City with pace and force their backline a little deeper. City are at their best whenever they have pure possession and control against the other, their wingers are poverty when in comes to counter attacking so they rely a lot on their fullbacks overlapping which slows their game down. If you force their line deeper, they have less control, the spaces between the lines are higher so that allows your team time to play, the likes of Hazard will have a few more metres of space so they can accelerate with pace. Near the end of the game if we were still ahead we put on Drogba to hold it up at the corner flag and slow the game down.
Don't think Chelsea were that defensive yday all factors considered though. We could have full on parked the bus from first minute but this was just a lethargic performance that nobody is to blame for.
In away games I see Mourinho do the opposite, we would have started Drogba away vs City, so that we have a guy capable of keeping possession high up the pitch in the early stages, then using Remy later on as a pace threat when the backline are a little tired.