That's the point. This thread is full of "we should be tighter at the back" and all these cliches, when the truth is the team picked itself because of injuries, and Aguero is misfiring worse than at any point in his career, Silva and Yaya aren't fit and Sterling, Otamendi and DE Bruyne are new to the team. It was a mad game of football but it was also one we deserved to win comfortably on balance despite all this.
As OB1 says, we went 5 games with our first choice centre halves and didn't conceed a goal. As soon as we lost both of them we started conceeding silly goals. That is, of course, not a coincidence.
I am not seeing anything whatsoever to worry about because every one of those problems will sort itself, barring long term injury of course. We are not losing midfield battles or getting overrun.