I didn't imply that a starting player doesn't need to improve.
He has improved massively already since being at City which is why he starts every week for a treble winning side. What he does effectively for City has nothing to do with his own goal tally though.
Now he regularly wins most duels, most take ons, most fouls won and most chances created in a game and is super consistent at that.
I'm not sure what's being asked of him could be translated into more goals without negating the other stuff he's doing well for the team.