Editor's note: This is the third in a series previewing the BSU football team by position. Monday: tight ends.

The Boise State football team's defense boasts good depth all over the field - except at perhaps the most critical position.

An injury and suspension have left the Broncos with just four game-ready defensive tackles. While sophomore starters Chase Baker and Billy Winn should be a dynamic duo, they won't play the entire game.

Behind them are sophomore J.P. Nisby and freshman Darren Koontz - two players who weren't expected to be in this situation.

"We've got to get those guys to step up and compete and get ready to play," defensive coordinator Justin Wilcox said.

The Broncos prefer to rotate their defensive linemen frequently. Last year, four ends and four tackles split time almost equally during games.

Baker and Winn likely will take on more than half of the responsibility this year, but coaches don't want them playing every down - particularly against fast-paced spread offenses.

"You need four guys, but there's different levels of that," defensive line coach Pete Kwiatkowski said.

Nisby and Koontz have been thrust into important roles by the suspension to freshman Michael Atkinson (at least three games) and injury to freshman Greg Grimes (out two-four games).

Nisby was the third option at nose tackle coming out of spring ball, behind Baker and Atkinson. He has improved in the fall, getting lots of work because of the lack of depth.

"His conditioning is better and his overall consistency and his practice habits have improved," Kwiatkowski said.

Koontz wasn't even on the radar at tackle after spring ball. He played end as a redshirt last fall and in the spring. Kwiatkowski told him this summer he would switch.

Koontz likes the move. It's the position he played in high school and he didn't possess the athleticism for end. At tackle, he's a bit light but quicker than most.

"I felt like I'd get lost in all that space out there at end," Koontz said. "É I just had kind of been waiting for (Kwiatkowski) to say it."

Koontz made a "huge stride" over the past week, Kwiatkowski said. The playing time for him and Nisby will be determined based on how well they perform in practice leading up to the Sept. 3 opener against Oregon. All-WAC end Ryan Winterswyk also could take some snaps at tackle if necessary.

"J.P. and Koontz definitely have stepped up this year," Winn said. "I've seen an exponential growth in their technique and what they've done. They've adapted to what we do here."

And both are eager to prove how much they've learned on game day.

For Nisby, it will be his first chance to get extensive playing time.

"I'm very excited," he said. "I hate waiting. This is the worst time of the year."

For Koontz, it will be his college debut and the culmination of a year of tedious work. He won an award last year for his commitment to the program as a redshirt.

"It might be a little nerve-racking for the first one or two snaps," he said. "But it'll be a lot of fun. You came here to play. You don't want to get cold feet or anything. I'll be ready."