His first year he should look decent, he uses a very high powered upbeat offense and has a QB that can put a lot of pressure on a defense.
His 2nd season will tell us what he really is. Either Murray is a stud and plays like Mahomes or the league figures out the gimmicky offense and shuts them down game after game.
Personally I think he will be a decent NFL HC for a number of years, he has an offensive mind and knows how to game plan. His main limitation will be Murray, if teams can slow him down the offense will sputter and they won’t be built for 3rd/1 or goal line situations unless it’s a sneak by Murray which will eventually get him injured in the NFL. I do think with a couple decent drafts that the Cards can be good again and also believe that he will get a minimum of 3 years there to make it work.