It's just going to take a little time until Manny finds "his team" he's given Dzeko some game time, but Negredo has taken every single chance he's had, so it's only a matter of time before he gets the nod.
Nasri, and Milner have been subs, and might just work their way into a starting team until things find their natural rhythm or when new signings sync
2nd half might be an indication as to where the team is heading, with a weakened back 4 and a bedding in midfield, Nasri and Milner might be preferred starters.
I certainly think Negredo and Aguero should have a crack as a partnership