BOISE - The secondary is often the last line of defense. But for the 2008 Boise State Broncos, the secondary is primary to the success of a defense that has aided a 9-0 season.

"I honestly think the strength of our defense is our DB's," senior safety Ellis Powers said. "We're physical in the run and we're great in the pass. We've got the best of both worlds back there."

Powers is probably a little biased since he is a starter in that secondary, but the proof is in the pounding. Powers (57), sophomore Jeron Johnson (60) and true freshman Geroge Iloka (36) are all in the top six in total tackles for BSU this season.

Powers is more of a strong safety, often playing closer to the line, covering underneath routes, tight ends and coming up in run support. He is second on the team with seven tackles for a loss. Johnson plays more of a free safety role, watching - and twice intercepting - the deep balls, but also coming up to stop plays on the edge.

Iloka has three picks and has recently played as a nickel back, a position usually given to an extra cornerback. But Iloka's speed and length are too much to keep him off the field.

"I think I'm a little bit more of a ranger, just getting to my spots," Iloka said. "You've got to be able to do it all."

With lockdown corners on the edge in Kyle Wilson and Brandyn Thompson, who lead the team with four interceptions apiece, the safeties can roam a little more than usual and pile up the tackles. Together they are No. 2 in the country in defensive pass efficiency (93.63) and in scoring defense (10.33 ppg). They are in the top 20 in every NCAA defensive category.

Johnson and Powers have a competition going this season, each vying to lead the team in tackles.

"It helps motivate you to make more plays," Johnson said. "Whenever you have some healthy competition going on, you're going to work harder. That's all it is, a little friendly competition."

Powers is the only defensive back not to grab an interception this season, but last week he recovered a fumble for a touchdown against Utah State - the only defensive score this season for BSU. Johnson said it didn't count.

"Nah, he didn't even know he scored," Johnson joked. "He'll get (an interception_ if he keeps playing like he's playing."

This week things might change for the secondary. Idaho runs a more traditional offense, away from the spread offense sweeping college football. Hence, BSU may go back to the 4-3 defense typically used and away from the nickel package that has been stalwart in an unbeaten season. This week look to see three linebackers in the game more frequently than in weeks past.

"It's not that the linebackers don't play hard, but we have 11 players out there and having five of them being DB's, it gives us a little extra edge," Powers said. "We're just working hard and making good things happen when we happen to be out there together."

Idaho is supposed to be primed to try and run against the BSU defense, but rivalry games seldom reveal themselves as typical.

"We have to be ready to stop the run and the pass, because they are still able to pass the ball," Johnson said. "We still gotta read our cues."

Iloka talked about the transition at BSU. He said he learned whole new ways to make a tackle. Once he adjusted and started to make sure tackles in space, he cracked the starting lineup.

"I have to keep my eyes low and make sure my feet aren't stuck in the ground," Iloka said. "If your feet are stuck in the ground, they'll blow right by you."

That hasn't happened a lot this season. The Broncos make their tackles, force turnovers and frustrate offenses to the point of stalemate. These safeties force frustration.

And it doesn't seem to matter who wins the contest between Powers and Johnson, because the Broncos are undefeated and in the end, that's all that matters.

Dustin Lapray covers BSU football for the Times-News. Read his blog at Magicvalley.com/blogs/bsu.