"I know it's a huge rivalry for everybody involved in it," Mattison said. "It's Michigan. It's Notre Dame."
He knows because he's spent eight years on the opposite sideline, coordinating the Irish defense under Bob Davie and then staying on staff under Tyrone Willingham to coach the defensive line.
"I had a great eight years there," Mattison recalled. "I got to see my family through school and my daughter in college, so that made it a really good deal."
Mattison left Notre Dame when the Willingham era ended, landing with Urban Meyer in Gainesville, part of a coaching staff filled with Davie lieutenants. From there, he became a perennial thorn in Irish fan's side, winning several one-on-one battles for high-profile recruits, and drawing the ire of Irish fans by allegedly using some negative tactics about all things under the Golden Dome to win.
Mattison's three year run at Florida was a successful one, but he jumped to the NFL to join John Harbaugh, a friend and coach he'd worked with early in his career under Harbaugh's father Jack. Mattison ascended to defensive coordinator after Rex Ryan was hired as head coach of the New York Jets.
While Mattison was coordinating one of the NFL's best defenses, ESPN.com's Michael Rothstein of Wolverine Nation nicely chronicles Mattison's unlikely return to the college game, a move he made only because of the man asking.
The NFL taught Mattison more about disguising blitzes and coverages and about how best to pressure the quarterback with schematics. It forced him to become more varied in his playcalling. For the first time, he didn't have to teach as much as he had to call the right scheme.
"He was a very good coach here," said safety Tom Zbikowski, who played for Mattison at Notre Dame and with the Ravens. "But with his personality and just him as a human being I think he works very, very well with young men. I think he can relate to them well and be a figure that somebody needs at that time of their life."
Mattison learned a lot. But his best friend called. He had just been hired as Michigan's head coach. Did Mattison want to come?
Back to college, back to Michigan, back to Brady Hoke he would go.
Hoke tasked Mattison with fixing a Wolverine defense that had falling apart under Rich Rodriguez. He's already gotten off to a quick start in his other forte, recruiting, with 15 of the 23 recruits already committed to Michigan set to play defense. Now he's got to get his defense ready to take on one of their biggest rivals, after it took a few lumps in its debut against Western Michigan.
When Mattison sat down with the media earlier this week, he discussed some of the difficulties his defense had against a Western Michigan unit that played an up-tempo, hurry-up scheme.
"The thing that happen is the kind of thing you worry about happening," Mattison said about his unit's opening drive. "When you had so many guys that hadn't played a lot football you probably had the toughest scenario you could get because it was a very fast pace. They were switching personnel groups in and out without us really being able to decide and see what they were."
No disrespect to Bill Cubit's Broncos, but when Tommy Rees took the helm of the Irish offense after halftime last Saturday, the Irish moved at a tempo that made Western Michigan look like it was running out the clock.
Mattison countered WMU's early success by bringing pressure, forcing turnovers from the Broncos after it was clear that Michigan couldn't get to the passer in its base defense.
"We won't sit back and play zone coverage until we have the ability to get a rush with a four-man front," Mattison said. "It's not fair to that secondary or that underneath coverage. If we get in a situation like that we'll always try to do what's best for the defense. I'm not going to say I'm a guy that's going to say he's going to go out and blitz every down, but when it dictates it, then I think you have to."
If there's a situation that dictates it, Saturday evening is it. With Rees moving the offense up and down the field in the second half, Mattison knows he'll need to protect a secondary that's still lacking in depth.
If there's a counter-punch to be had by Brian Kelly and the Irish coaching staff, it's a running game that can be the biggest offensive asset Notre Dame possesses. Lost in last Saturday's defeat was Cierre Wood's performance, a dynamic effort as a runner, who also made big plays in the passing game as well.
Mattison understands that while Rees, Michael Floyd, and the Irish's other aerial weapons can hurt Michigan, they'll need to make sure Wood doesn't take over the football game.
"We have to be able to stop the run," Mattison said. "Any time a team runs the football on your defense, you can't have a great day."
Brian Kelly made the change to Tommy Rees in large part because he knows Rees is undefeated when he has both a run game and passing attack at his disposal. If the Irish are going to get their season back on track in front of 110,000 fans in Michigan Stadium, they'll need to have both.