So far Manchester City played in many games without their effective and important player Kevin De Bruyne and they mostly had bad performances while just after he got back to the field they got much better results and had much better performance. However, Manchester City lost many points so far, and getting back to the first place in the league won't be easy even for them.
It cannot be denied that conditions were like that at that time. that's how important de Bruyne's work is for Man City. Indeed, Man City was still strong at various occasions without de Bruyne, but it was not as effective and not as excellent when de Bruyne was in the game. Because de Bruyne is a key player who really influences Man City's playing style and also their performance. so that when he returns from injury, his abilities are still very reliable.