One thing I noticed last night was that any time an Ajax player got to a loose header in the middle of the pitch it almost always went to another Ajax player. Whereas almost every time a city player did the same thing it mostly went no where near a team mate.
It might seem like a small thing but it was a big reason why they kept the ball and we didn't. Do we practice keeping the ball by headers? It would seem a small thing which would have a big benefit.