Alvin Bowen led the ISU football team in tackles the last two seasons and was the heart and soul of the team’s defense. Finding a replacement for him and fellow outside linebacker Jon Banks might make or break, when it comes to the defense’s success this season.

“We lost two starting linebackers, both of whom are in the NFL right now,” said coach Gene Chizik. “When you have those people to replace there are concerns, but the bottom line is: No excuses. We have to develop a front seven; and it doesn’t matter who it is, it’s just got to get done.”

Junior Fred Garrin will get the first chance to pick up where Bowen left off. Garrin saw limited action last year and made 19 tackles.

“You’re going to have to get used to the names down there because you won’t have heard of them,” Chizik said.

Starting at strongside linebacker will be senior Michael Bibbs. Bibbs finished last season with 19 tackles and two pass breakups.

“We’ve got some young, talented players, it’s just a matter of them coming out on Saturdays and doing their job,” said middle linebacker Jesse Smith.

At 6 feet 1 inch, both players would be considered undersized by Big 12 standards, but both Garrin and Bibbs are known more for their motors and athleticism.

The sole returner in the linebacker corps is middle linebacker Smith. Smith started all 12 games last season as a sophomore and is the leading returning tackler from last year’s team, forcing him into a leadership role.

“The only thing that I can teach them is to do their job on every play,” Smith said.

The outside linebackers aren’t the only concern for the defense. The Cyclones also need to replace their two starting defensive tackles from last year.

Trying to fill the large shoes of Athyba Rubin and Bryce Braaksma will be a handful of new faces. The starters, for now, are Michael Tate and Nate Frere, but Chizik expects the defensive tackle position to be a revolving door.

Defensive coordinater Wayne Bolt said the competition is high on the defensive line and a number of players will see playing time.

Finding the right players to step up at these four crucial positions could determine how good this defense can be. Last year’s defense ranked sixth in the Big 12, defending the run. With an improved pass defense, Chizik said a large part of defensive success hinges on stopping the run.

“I think everything starts on defense in the front seven, so obviously that’s a huge, huge part of us,” Chizik said.