You are right, from the beginning of the season Manchester city has been in a very terrible form and this isn't the team we once knew...I remember that Manchester city we all believed in, they always delivered when it comes to comeback goals and it was hard for them to get defeated...This new season is actually different for them, I don't know what their problem is and I am not optimistic about them winning the title this year as well
Perhaps the loss of Kevin De Bruyne is one of the reasons for Manchester City's decline in performance.
The player hasn't looked like a key player after a long injury layoff, but he's nonetheless a key player who consistently supports Erling Haaland in scoring the winning goals in every match.
What's happening now is really just about getting the right players to achieve more consistent performance.
When Manchester City gets premier league trophy De Bruyne is one of the key player of Manchester City and even so with Rodri and when these players under perform usually Manchester City unable to beat their opponents so, this time you said is true that recently on their squad there are no players who can able to replace their position and do not forget too besides these players i think some players too has difficult to found his shape again
For an example that the fans probably notice this that the performance of Manchester City goalkeeper Ederson in the last few season is decreases that he was quite often to make blunder which caused Manchester City lost points so, i think this is also the weaknesses and this factor too makes Guardiola dare to buy Donnarumma and probably he will being an the replacement of Ederson on the main squad