Not sure why anyone would be surprised, they have a fantastic squad, arguably the best player in the league when he's at his best, arguably the best midfield in the league now, a manager that plays dominant football that will get the fans fully behind them, and most of all, they go up and down every season. They walked the title with Mourinho, then collapsed. Walked the title with Conte, then collapsed. We'll see how they do this season, but everything pointed towards a big boost especially with nothing but the premier league to focus on (he'll probably bin the Europa League or just play back ups, he did the same at Napoli).
I've been saying from the start that while City are obvious favourites, Liverpool and Chelsea could equally push them but those are looking like the top 3 both on paper and expectations.