This is true.
Mahrez moved around the pitch much more last season. This season, the team has not been anywhere near as much on the front foot and bold. This has affected Mahrez more than anyone.
One example. Remember on loads of occasions last season when the opposition had a corner and we put two or three players (Mahrez always being one of them) on the half way line. Scared the shite out of teams that did, whether it worked or not. It was aggressive, it was confident, and it said, 'feck your attack. we're still going to get you'.
Every corner now and all eleven of our players are back in our own penalty area. It's about safety first, it's about the fear of failure. And that, in a nutshell, is the entire reason why Mahrez isn't the same player this season.