Manchester City still have the firepower even against Arsenal they displayed a lot of it. Arsenal where more defensive and containing the city side, while city where more aggressive in the attack.
Yeah that was the Arsenal strategy on that match they were playing a defensive game and it really work for them, Pep Guardiola has really thought Arsenal coach Mikel Arteta very well, he has known that Manchester City has more greater performance than Arsenal and the only strategy to counter there plan is through defensive play.
If you check on there possession Manchester city has more good number of possessions than Arsenal but with there defensive strategy Manchester city was finding it a bit difficult to break, although with the performance of Manchester city on that match I never believe Arsenal will be able to beat them.
But if De Bruyne and Rodri was on that match it would have been very difficult for the Arsenal team because De Bruyne is a playmaker of Manchester city and whenever he is not there the team easily get affected.