East Lansing — With Pat Narduzzi now planning to take over as the head coach at Pittsburgh, there are some interesting times ahead for Michigan State.

After eight years putting together one of the top defenses in the nation, the 48-year-old Narduzzi is getting his shot to be a head coach, one that has seemed inevitable for the last couple of years. While a huge opportunity for the Spartans' defensive coordinator, it creates a fairly large hole in East Lansing.

His performance has been clear just based on the numbers the defense has posted. In the last four seasons, Michigan State is one of just two FBS schools, including Florida, to rank in the top 10 in the nation in total defense. The Spartans were second overall in 2013 and are seventh this season heading into their Cotton Bowl matchup with Baylor on Jan. 1.

It's all a result of the defense Narduzzi has created in East Lansing, one that focuses on press coverage from the corners and an aggressive pursuit of the quarterback. The Spartans have been among the leaders in both rushing and pass defense and this season led the nation in turnover margin (+1.67 a game).

Most of it has come from the work of Narduzzi and Michigan State head coach Mark Dantonio, who have been together since Dantonio became the head coach at Cincinnati in 2004 after winning a national championship as defensive coordinator at Ohio State.

The defense has evolved over time, but Dantonio was clear before the season that Narduzzi has been the architect.

"We were a 4-3 team in Columbus, a big zone pressure team when I was there," Dantonio said before the season. "We are still a big zone pressure team. We are still a 4-3 team, but it is different. The majority of (those changes) was Pat Narduzzi and his defense. When we got together at Cincinnati, we combined the two when I was first a head coach. It has gradually evolved towards his way.

"He is a defensive coordinator. I'm a defensive coach. I am going to know what's going on, but he is our defensive coordinator, and it starts there."

How Dantonio adjusts at this point will be critical for the Spartans. After eight seasons at Michigan State and three at Cincinnati, Dantonio will be searching for a new defensive coordinator for the first time in more than a decade.

A good indicator of where he'll look first is the fact that not only has Narduzzi been with him for 11 seasons, but so have defensive backs coach Harlon Barnett and linebackers and special teams coordinator Mike Tressel.

Narduzzi has often praised his assistants for their role in creating Michigan State's defense, so it would seem logical that one, or both, could step in to take over for Narduzzi. Both aspire to be a coordinator, and Dantonio has leaned often toward promoting from within.

However, each could be a possibility to follow Narduzzi to Pittsburgh. There likely won't be a fight over assistant coaches, but Dantonio could offer Barnett and Tressel co-coordinator spots to keep them from leaving and to maintain some continuity.

Each has had plenty of success. Barnett has coached the likes of Jim Thorpe Award winner Darqueze Dennard, and this year cornerback Trae Waynes appears to be a potential first-round draft pick. Tressel has seen his share of outstanding linebackers come through the program, including the likes of Greg Jones, Max Bullough and Denicos Allen.

Dantonio will hope the environment at Michigan State is enough to keep them around.

"What I've tried to do is make it very apparent to our coaches that they have a place to be, they have a great place to be, a great working environment," Dantonio said.

"And I'm gonna empower them as coaches. When the time comes for them to leave, they should leave for the right job. The right situation."

Michigan State could look outside to replace Narduzzi and that list likely could grow quite long. Dantonio has gone both ways in the past when an assistant moved on to become a head coach.

When running backs coach Dan Enos left after the 2009 season to take over at Central Michigan, Dantonio went outside the program and hired Brad Salem, who was then the head coach at Augustana College.

And when Don Treadwell was named head coach at Miami (Ohio) after the 2011 season, it was offensive line coach Dan Roushar who was promoted to offensive coordinator.

With Dave Warner and Jim Bollman in their second year as co-coordinators on offense, Salem could also be a possibility to follow Narduzzi.

But maintaining a dominating defense will be the key, and it will be even tougher for the next guy, considering as many five starters could be gone by the time next season starts.

However it shakes out, coaching changes will continue to be an issue for Michigan State as long as the success it has had over the past five seasons continues.

"That is the nature of it," Dantonio said last week. "When you're successful as a program, that is the nature of it.

"People say, 'How are they doing that at Michigan State? How is that happening there? These guys must be responsible for that.'

"They want to hire people like that, and I think that's a good problem to have.

"Part of my job is to try to build opportunities for other people, whether it's players or whether it's coaches. So when those things happen, I think that's a positive for us."