Michigan defensive end Ryan Van Bergen (53) runs through drills in practice before the Sugar Bowl against Virginia Tech on Tuesday. (Gerald Herbert/AP)

Michigan defensive lineman Ryan Van Bergen thought he had seen and heard it all during his previous four years in Ann Arbor, from being a part of Lloyd Carr’s final team in 2007 to the tumultuous three years that followed under Rich Rodriguez to finishing the 2010 season with the third-worst defense among Bowl Championship Series conference teams.

But then one day this past spring, new defensive coordinator Greg Mattison popped in some video of the Baltimore Ravens, his previous coaching stop, and told the 288-pound Van Bergen he wanted him to emulate defensive tackle Haloti Ngata.

“I was like, ‘So you want me to play like Haloti Ngata?’ ” Van Bergen recalled this week. “He was like, ‘Yeah,’ and gave me the shrug like I’m crazy for not knowing what he meant. ‘Haloti Ngata is 330 [pounds]. I’m not Haloti Ngata, coach.’ ”

The Wolverines can laugh about those first days under a new regime now, but when Michigan takes the field Tuesday to face Virginia Tech in the Sugar Bowl, it will be the final validation for a coaching staff and a defense that have been the catalysts for a dramatic culture change at the winningest program in college football.

A year after ESPN analyst Chris Spielman referred to Michigan’s defense as “a bunch of guys who would be nice little subs at Indiana,” the Wolverines have improved to 17th in the country without making significant personnel changes. Instead, as Virginia Tech’s coaches have pointed out several times this week, it has been Mattison and first-year Coach Brady Hoke’s ability to “coach them up” that has led the Wolverines to their first BCS game since 2007.

“These coaches just really understand the Michigan tradition,” defensive end Craig Roh said. “They’ve brought it to life through practice, through camp, through all that stuff. It has enlivened all of us right now. I think that’s why you see, I guess, a change in the environment.”

When Hoke and Mattison first returned to Ann Arbor — Hoke was a defensive line coach when Michigan shared the 1997 national championship and Mattison was the Wolverines’ defensive coordinator in 1995 and 1996 — they encountered a team that “broke every record you didn’t want to break as a team,” Van Bergen said this week. “I would think that we have a blueprint as far as what not to do.”

Enter Mattison, who had spent the past two years as the Ravens’ defensive coordinator when his good friend, Hoke, called one day wondering if he’d be interested in returning to the college ranks.

To the surprise of some, Mattison took the job rather than staying in Baltimore to coach Ray Lewis and Ed Reed.

“I just missed the chance to take some young man that maybe is not a great football player, or people say he’s not a great football player, or he doesn’t believe he’s a great football player, and help him get to become as great as he can,” said Mattison, who added he wouldn’t have made the move if it were any other school. “That’s something that I’ve always enjoyed in all my years of coaching and I missed it.”

Mattison brought with him the complex coverage schemes of the NFL and blitz packages that are so extensive Virginia Tech offensive coordinator Bryan Stinespring said recently, “It’s almost like they’ve got a different playbook.”

The end results are evident on the scoreboard.

The Wolverines have gone from giving up more than 35 points per game in 2010 to allowing just more than 17 points per contest this season. Michigan never finished higher than 67th in the country in total defense under Rodriguez, but with players almost exclusively recruited by previous regimes the Wolverines moved up to 17th this year.

But for a unit that had “experienced so much pain and suffering,” according to Roh, it was Mattison’s tacit belief that seemed to make all the difference. And so even though Van Bergen still jokes about being compared to Ngata, he’s more than happy to point out just how far this defense has come.

“I don’t think it had anything to do with buying in. It was more about staying in. When things started going wrong, you could see the team kind of fall apart a little bit,” Van Bergen said of past seasons. “Guys didn’t want to be too committed because if you’re too committed and things start going wrong, you can take a lot of the blame. . . .

“We’ve been through the worst of fires, we’ve been through the worst that can happen to us, so whatever these coaches tell us to do, let’s make sure we don’t have any regrets. We’re sitting here right now and I don’t think there’s a guy on the team probably too regretful about anything.”