De Bruyne is still being slowly integrated back into the team because they are being cautious with him. He did have some serious injury problems last year and in the first couple of matches of the PL in this season the coach took him off when the result and win were secured. He has started very well and has an assist in every PL match so far.
Pep is being very careful with Kevin and i can understand why, I do not think he's completed any epl game this season, he is usually taken off for the final 20 minutes to give him a breather as he still tries to fully recover from last seasons incessant Injuries.
City need Kevin and it's most especially in the later part of the UCL, his creativity can help City in tight UCL knockout games. If he can stay fit all season, I think city are already guaraneed two titles or even more.
Mane is good and young winger but he is too inconsistent, no wonder why he mostly came as substitute or remained as bench-warmer last season
do you actually mean the mane of Liverpool? I do not think so, Mane was a mainstay in the Liverpool team last season and his performance was excellent all season long.