If the first substitution by Manchester City indicated a minor tactical adjustment, this one signals a major tactical adjustment. Roberto Mancini has given the people what they want, making the Manchester Derby infinitely more interesting by bringing in Edin Dzeko to challenge Manchester United's back line. The striker replaced midfielder James Milner, who on top of having a generally poor game, appeared to pick up an injury just before he was substituted. In case Mancini was planning on subbing off a different player for Dzeko, which seems unlikely, his hand was forced when Milner started limping around.
For the entirety of the second half to this point, much like the beginning of the first half, Manchester City have been in control, but well held by the Manchester United defense. Edin Dzeko could change this significantly. On top of his great touch and nose for goal, Dzeko adds an element to City's attack that they did not have before with his size. City are now lining up the way most neutrals wished they started the game, and they're probably about to look dangerous as a result.