The ISU football team’s main concern on defense this Saturday can be summarized in one number: 6.2.

The Cyclones (2-0 overall) have allowed a troublesome 6.2 yards per carry to opposing offenses entering Saturday’s rivalry game with Iowa (2-0).

Hawkeye running back Shonn Greene has amassed 239 yards on 35 carries and runs behind the most physical offensive line that Iowa State has faced thus far.

“Our front 7, right now, is not very good against the run,” said coach Gene Chizik. “Look at the stats — that’ll tell you everything you need to know. If we play defensively against the run as we have in the first two games, right now, we won’t fair very well on Saturday.”

The defensive yardage totals are skewed by an unlikely 86-yard fumble recovery and touchdown run on South Dakota State’s final offensive play of the season opener.

On first-and-10 from the 14-yard line, Jackrabbit running back Kyle Minett made a 6-yard gain before the ball was knocked out of his hands. It caromed forward, through the ranks of the Iowa State defense and into the hands of wide receiver JaRon Harris, who scooped up the ball and out-ran the Cyclone defense.

Excluding that play, Iowa State is allowing 5 yards per carry. Kent State quarterback Julian Edelman and running back Eugene Jarvis gave the Cyclones fits last Saturday, combining for 204 rushing yards and eluding ISU tacklers throughout the game.

“I don’t have the answer other than we’re going to continue to work in that area because it cost us points [Saturday night],” Chizik said after the Kent State game. “Most important, it cost us points, it cost us yards, and it cost us first downs, and it cost our defense to stay out there longer.”

Iowa State lost the interior of its defensive front-seven to graduation, including NFL draft picks defensive tackle Ahtyba Rubin and linebacker Alvin Bowen, as well as multi-year contributors linebacker Jon Banks and defensive tackle Bryce Braaksma.

Junior nose guard Nate Frere said he had to do their job on every play.

“It’s a team thing,” Frere said, who appeared in eight games last season. “If I don’t maintain my gap they could rip it for a touchdown. If a linebacker doesn’t fill his gap, they can rip it for a touchdown.”

First-year starter Michael Tate, sophomore Bailey Johnson and true freshman Stephen Ruempolhamer compose the three-deep rotation at defensive tackle. Johnson is the only tackle with returning experience, having appeared in 11 games last season.

At nose guard, redshirt freshman Jerrod Black and sophomore Austin Alburtis are receiving their first playing time. Iowa State’s two new starting linebackers, senior Michael Bibbs and junior Fred Garrin, saw regular action off the sideline last season, as did junior backups Josh Raven and Derec Schmidgall.

Sophomore Justin Rumple and true freshman Ernest Ferguson have also logged time at linebacker.

Overall, Iowa State has played 11 true freshmen, five redshirt freshmen and 19 sophomores in the first two games.

“We’re not a very good football team in a lot of ways, so we’ve got to go out there and get a lot of things accomplished in the next three days of practice,” Chizik said on Monday.