Injuries to several key players will be a problem if a coach relies heavily on individual player skills rather than game tactics. But it is very natural that injuries to key players will affect the team's game as a whole. This is the same as what Barcelona experienced last season and City currently. Injuries are a problem for every club, especially since every season we see more and more matches because UEFA has many tournaments in their calendar. Ancelotti must be able to rotate players if he wants to be on the path to becoming a champion. But I doubt that because I have not seen Ancelotti in his current condition in the previous season. If he can rotate players well then he is not a "tactically poor" coach as reported in some media.