How many of our results this season do you think would have been different if you had swapped those players?
Mahrez has had very few decent performances in the league this season, has created precious few chances all season and he certainly isn't picked for his defensive qualities.
People question Okazaki's position in the team, understandably, because he doesn't score or create enough, but most games he at least presses the opposition and makes runs to create space for others. What exactly is Mahrez's contribution that makes him irreplaceable?
Mahrez was an average player before last season and has been a liability more often than a match winner this.