If one were to discuss Manchester City's most important players, I think the first names that would come to mind would be KBD and Rodri. These two players are Manchester City's attacking midfielders as well as the great finishers the team needs at times, but unfortunately both players have suffered long-term injuries at the same time this season which has led to concerns over their injury management.
They are most important players of Manchester City but because of ageing effects, role of Kevin now is less than some seasons ago. He is still important player in Manchester City but maybe no longer a first or second most important player there.
Rodri is most important player in Manchester City because he plays in the midfield and has good ability to keep balance of their system between attacking and defense. Rodri has good ability to score important goals for Manchester City and he is like an ace up their sleeves. His goal for Manchester City in a Champions League final match is an example.
KBD was most likely out of action last season too with an injury and was expected to make a strong comeback in the upcoming season but failed to do so. Since two important players of the team are not with the team at the moment, Manchester City will hire new players instead of these two or they will continue this season with their old players, but it is not yet clear from the team.
Kevin can still play very well but his appearances in Manchester City squad become less and less. Because he is older and gets more injuries with time as well as needs more time for recovery. He will be like many players who will have worse bodies and performances with time.
Rodri is going to be out for the remainder of the season due to his ACL injury. Rodri is an important piece to Pep Guardiola’s game plan. His long absence will affect the team’s performance but I don’t think it will affect Manchester City title race this season. Manchester City have the money and will buy replacement in January. I believe Pep is playing mind games with his recent comments.
ACL is the most fearful injury type with football player and with this injury, Rodri lost this season but maybe more than that. It will make his body less vulnerable to more injuries in future after he recovers from this one.
This serious injury of Rodri and his absence in rest of season will change a lot of Pep Guardiola's plans for Manchester City. They will be affected a lot by this accident because for many seasons, Rodri is almost irreplaceable defensive midfielder in Manchester City.