I think if you look closely there's a pattern that's emerged with pretty much every City attacker under Pep at some point. Before Pep showed up/they were signed by Pep, they were these extremely high skill players with technical potential to rival the best.
But after decent starts, they all went through spells of losing that flair, subsequently becoming weaker players for us. However, almost as if by design, these periods coincide with these players becoming more functional for us; they start developing into better players for the team.
Then, later on, they start to come back out of their shell and now are both functional to the team and exciting flair players like you thought they were.
Basically, I'm pretty sure Pep has them cut out a lot of the super-exciting stuff until he's sure they understand and are able to play the right way. Then they're back on it.
Sterling being the prime example, but Sané, Bernardo, Jesus, Aguero (to an extent), and somehow Fernandinho have all gone through or are still going through this process. There were even signs Mendy was cutting out his more attacking elements in favour of functional play too prior to his injury.
I think whilst Mahrez adapts we're not going to see the full him. Think about how many times he's probably had to ask himself, 'Do I do my thing or Guardiola's thing?' when in a good position. That's not what a player in full flow probably has to worry about.
I can't say for certain that he'll work out. But given the trends that seem to reoccur in this squad I think we should give him time.
