We weren't poor.
Everton had almost no chances. They had one shot from about thirty yards out which was blocked, and they had the shot they scored from. Players rarely curl in shots from the edge of the box, but occasionally they'll get lucky. Yesterday they got very lucky.
City created plenty, but didn't score as much as their play deserved. The number and quality of chances was pretty much the same as in the three games we scored 4 this season. While Demarai Gray would probably miss the next twenty times he tried the same shot, Stones and Rodri would expect to score regularly with the attempts they had yesterday.
Everton may be poor, but their defence is top 6, and only significantly bettered by the top 3, yet if that match was played out a hundred times, with the same chances, we'd win almost every one of them.
These games happen. City don't always play well, but against Everton they played well but didn't have the luck on the day.