LINCOLN, Neb. -- The reality hit Nebraska defensive coordinator John Papuchis while he watched his charges run a step behind the UCLA Bruins and miss an alarming number of tackles.
The Cornhuskers have a need for speed.
"Team speed has been a little bit lacking over the first couple games, so we're going to try to get some of our faster guys on the field and see how that works this week," Papuchis said. "Everybody is in the equation. If we have to work 24 hours a day for the next seven days or, really, for the next three months to figure it out; we're going to figure it out."
The Huskers (1-1) are 115th nationally in rushing defense, 96th in total defense and 83rd in scoring defense after their 36-30 road loss to UCLA. They'll go against another spread offense when Arkansas State (1-1) visits Saturday.
Papuchis' most pressing concerns are at linebacker and defensive line.
Freshman David Santos and junior college transfer Zaire Anderson have been practicing with the No. 1 defense this week, and one of them could bump weakside linebacker Alonzo Whaley from the starting lineup.
Whaley struggled with positioning and tackling against the Bruins, who amassed 653 yards -- the second-most ever by a Nebraska opponent. Whaley and his teammates combined to miss about two dozen tackles.
Nebraska also was unable to consistently pressure UCLA quarterback Brett Hundley or do much to control the running of Johnathan Franklin.
Defensive line coach Rick Kaczenski said freshmen tackles Kevin Williams and Aaron Curry and end Avery Moss will be more prominent in the rotation against Arkansas State.
"That's the future," Kaczenski said. "Those guys, you're going to see more and more of them."
The question is whether the young players are truly ready.
The defensive line plays a challenging two-gap system that Bo Pelini has favored since taking over at Nebraska in 2008.
In a one-gap defense, the linemen are encouraged to shoot through gaps in the offensive line and get into the backfield to make a play. In two-gap, linemen are responsible for particular gaps, and they then try to shed blocks, clog the line and force runners into the arms of a lineate or linebacker.
Anderson, who played sparingly the first two games, told reporters he has had difficulty grasping coach the scheme.
"It was all thrown in front of me and it was hard," he said. "When I was in junior college, I just had to learn my position. Here, you've got to learn everyone's position. ... When your playbook is harder than your homework, that's a problem. I think it's harder than my homework."
Like Anderson, Curry said he has struggled to learn the defensive concepts, though he added that the playbook isn't as tough as his academic homework.
"I'm fresh out of high school and we didn't really run that many plays," Curry said. "Here, it's a lot more. I've been doing a decent job of getting the plays down. I need to get better."
Kaczenski, who taught a two-gap system as Iowa's defensive line coach the past seven years, said he has confidence all of Nebraska's linemen are strong enough and talented enough to be successful.
"A lot of it is just getting the experience and learning the different techniques and understanding the game and leverage," Kaczenski said. "All the guys are capable of doing it. The young guys are really explosive and physically mature for their age."
Ideally, Kaczenski said, the coaching staff would have a better grasp of the defense's personnel after two games.
The UCLA embarrassment showed the staff has more work to do to find the right combinations.
"The train is moving, and we've got to get on," Kaczenski said. "It's not slowing down for us. There are no excuses. There are no gray areas. Either you get it done or you don't. We really haven't gotten it done in either game up front."
Papuchis said time is of the essence. The Big Ten opener against Wisconsin is at the end of the month.
"These next two weeks are huge for us," he said. "We live by taking it one day at a time. The reality is that we need to be closer to where we need to be on Sept. 29."