Ends Demarcus Lawrence and Sam Ukwuachu and safety Darian Thompson were three of the most important figures on the Boise State football team's defense last season.

None had played major college football before.

They're back for year two - and what coach Chris Petersen hopes will be significant growth.

Lawrence, now a junior, led the Mountain West with 9.5 sacks and forced four fumbles to earn first-team all-league. Ukwuachu, a sophomore, added 4.5 sacks and three fumble recoveries to make the FWAA Freshman All-American team. And Thompson tied for second on the team with three interceptions and finished eighth in tackles (43) despite starting only the final six games, seamlessly filling the void left by suspended Lee Hightower.

"You're looking for them to take the next step and become dominating players because they all had good years, but we're looking for better than good," said Petersen, whose team will hold its fourth spring practice Saturday. "We really want elite players and dominating players, and all those guys will have a chance to do that with tremendous focus and hard work.

"Like I've said for many years, it's pretty easy to go from average to good when you're new - and that's sort of what they did. But to go from good to elite, that's very, very hard and a lot of guys can't get there, but that's what we're hoping can happen with these guys."

LAWRENCE

The transfer from Butler CC in Kansas made a strong impression last spring and won a starting job in fall camp. He recorded a sack in five straight games at one point.

"We just want to continue to build on that. The more comfortable he gets and the more confidence he gets in the techniques and the fundamentals, the faster he's going to be able to play and the more of his ability he's going to use,'' defensive line coach Andy Avalos said.

Avalos wants to see Lawrence "grow off the field." His season was somewhat diminished by a pair of suspensions for violating team rules, including the bowl game against Washington.

"He's working down the right path with that stuff right now," Avalos said. "He can be a leader for this team if he does it the right way."

Said Lawrence: "I made a couple of mistakes last year, but everybody makes mistakes. Try to move forward and stay out of trouble."

On the field, he developed an appreciation for the details of his position last season and hopes to refine those.

"First, I'm trying to work to get stronger, bigger, faster," he said. "Second, I'm taking more coaching and learning what I need to do better. … I feel like if I had been stronger at reading my keys I probably would have been a lot more productive than I was last year."

One way he pushes himself to improve is by competing with Ukwuachu, the lanky speed rusher on the other end of the line.

They trade barbs in the locker room and consider each pass play a race to the quarterback. Ukwuachu likes the approach he has seen from Lawrence this year.

"I've just seen the want-to in his eyes," Ukwuachu said. "The want to be one of the greatest in the country."

UKWUACHU

The 6-foot-4, 232-pounder figures he has watched each game from his freshman season at least 20 times.

"Now that I have a year under my belt and know the system fully, I want to cut out the little mistakes," he said.

He also hopes to improve his physicality - and that starts with his weight. He has added 10 pounds since last season, an ongoing battle for him, and hopes to top 240 by August.

He knows, as Petersen points out, that it can be a challenge to improve upon a good season.

"Just persistence and stay hungry, stay humble" Ukwuachu said of his plan. "Keep having the drive to get better."

He should be more versatile this season. He plays the stud end - the one that lines up on the defensive line or as an outside linebacker, depending on the situation.

His experience allows the Broncos to use the linebacker option more often.

"Sam is a talented pass rusher and he loves to pass rush, so we're fired up about developing his abilities this spring," Avalos said. "… We want to expand his net a little bit."

THOMPSON

It was this time last year when Thompson hinted of the breakout season to come.

There just wasn't a spot for him in the lineup.

"We knew going into training camp of 2012 that he had a chance because he knew all the positions and was making plays in practice," defensive backs coach Jimmy Lake said. "And sure enough, when his opportunity came, he cashed in and made a lot of big plays on game day. And we're expecting that from him again."

Thompson enters this spring as a returning starter and, despite his own youth, as a player Lake counts on for leadership in an inexperienced secondary. Junior Jeremy Ioane returns at the other safety spot, but most of the defensive backs have little game time.

Thompson is trying not to let his status change his approach.

"I play as if I'm not a starter," he said. "I play as if I need to get better."

Still, there are benefits to the experience he gained. Most notably, he can think less and react more.

"I'm just ready to go and play and have fun," he said.