The Tigers have new coordinators on both sides of the ball, so they'll present a different look when visiting Mullen's Mississippi State squad on Saturday (11 a.m., ESPN).
"We look back at last year's game a little bit, but they run a new offense and a new defense, so that game has really lost a lot of relevancy in preparing for this week's game," Mullen said.
So, what exactly can MSU expect to see? Good question, because it seems Auburn is trying to find its identity, especially on offense.
The Tigers lost to a ranked Clemson team in their opener, 26-19. New starting quarterback Kiehl Frazer was 11 of 27 for 194 yards, one touchdown and an interception. The running game produced 180 yards at 4.9 yards per carry.
New coordinator Scot Loeffler, formerly of Temple, Florida and Michigan, has added some pro-style looks to the spread that was run by predecessor Gus Malzahn. Auburn head coach Gene Chizik said he was "proud" of the way Frazier ran things in his first college start.
"I feel like he knows how to prepare now, he knows what to expect on game day, he knows what it's like on a Friday night before the game and getting his mind right," Chizik said. "There was a lot of first-time things that I think he's comfortable with that he's plowed through."
Mullen said he's certain Auburn didn't show its full hand against Clemson, which makes game prep even trickier.
"We're going to have to be kind of prepared for the unknown in this situation," Mullen said.
Auburn's defense is now being run by Brian VanGorder, a former NFL assistant. MSU receivers coach Tim Brewster, who also spent some time in the NFL, said coaches have been looking at some of VanGorder's work with the Atlanta Falcons, where he was defensive coordinator 2008-11.
Brewster said they are "trying to study the path and history of VanGorder." Earlier this week, VanGorder said he needed to see a lot of improvement from his defense this week, especially in the tackling department.
"I think he's a sharp guy, a veteran, experienced guy who's certainly going to fit the personnel to the system," Brewster said.