#3 The squad depth at Guardiola's disposal is frightening

Kevin De Bruyne was injured. Bernardo Silva filled in, as he has done impressively this season. Sergio Aguero had a knock. Gabriel Jesus, one of the best young players in the world filled in. David Silva was afforded a rest. Ilkay Gundogan, another elite midfielder, filled in.
Simply put, it's just scary. Guardiola has backups to his starters who would walk into most lineups in the division. The likes of Gundogan, Jesus, Mahrez, and others will arguably not make his strongest eleven, but they are content with a place on the bench, ready to fill in as and when needed.
Benjamin Mendy and Kyle Walker did not play for contrasting reasons, and Oleksandr Zinchenko and Danilo deputised for them. Now this tremendous depth is largely due to the finances available at Manchester City, but for whatever reasons, they have one of the strongest sides in world football. As a busy December awaits them, it will certainly come useful then.