I get that, but when we are discussing Manchester City, they should never depend on one or two injuries in a way that destroys the whole season if that happens. Yes it can happen and if Messi was to get injured back when he played for Barcelona, it literally meant that the game is going to be completely different. But they should still be able to compensate for these incidents on a level that the season is still not that much at risk. It does change the trajectory of a season, but it shouldn't to the extent that it is game over as soon as an important player misses a lot of games.
What you said is absolutely right because a team like Manchester City should be able to find a balance of power more so that they can still be strong when one or two key players are injured. Because if that is the only thing that can destroy them from a good position to a bad position, of course it would be a shame because they should be fighting for the title again this season. The next game for Manchester City is at home to Tottenham who are also in a bad shape at the moment, so Manchester City should be able to win at home without any excuses.