Here is a table that compares actual goals for and against with xG/xGA (expected goals for and against based on the rough quality of chances for and against).
To help read the table and looking at City first, we have actually scored 60 goals and let in 35 with a goal difference of 25. Based on xG/xGA we should have scored 65.9 and let in 26.2 with a goal difference of 39.7. Overall our actual goal difference is -14.7, call it -15, WORSE than on our expected goal difference based on quality of chances for and against. This is the worst in the league.
This tells us something we all know already and Pep bangs on about all the time and that is we have had problems in both boxes.
However, where it is interesting is when you compare it against the other teams. Our xG total is 65.9 which is by far and away the best in the league and is indicative we are the best attacking side. Our xGA total is 26.2 which is only a tad worse than the 2 best defensive sides United and Chelsea.