No position on the Boise State football team will look more different in 2012 than defensive end.

Gone are Shea McClellin, Tyrone Crawford and Jarrell Root, who combined for 15.5 of the team’s 24 sacks last season and are in NFL training camps right now.

Enter sophomore Demarcus Lawrence (Butler Community College transfer), redshirt freshman Sam Ukwuachu (2011 recruit) and sophomore Beau Martin (Colorado State Pueblo transfer) — three guys who haven’t played a single snap of major college football.

Lawrence (6-foot-3, 242 pounds) and Ukwuachu (6-4, 222) are an intriguing pair because of their athleticism, which was apparent through the first week of fall camp. They have good speed and have shown the agility and awareness to bat down passes around the line of scrimmage.

“We hope to get a lot out of them because we really don’t have a choice,” coach Chris Petersen said. “Those guys have got to come in and produce. I think they will, and I think their futures will be pretty bright. They will continue to get better and grow because they are so new. … They’re athletic, athletic guys — so that’s a nice starting point.”

The Broncos’ only returning ends are sophomore Tyler Horn, who made seven tackles and 1.5 sacks last season, and junior Kharyee Marshall, who didn’t make a tackle. Senior Darren Koontz, who made five tackles last year, also could play end but likely will be needed at tackle.

That puts pressure on Lawrence and Ukwuachu to perform immediately.

“They both bulked up a little bit over the summer and they’re working hard,” Koontz said. “They’re trying to master the end position. They have that speed — that’s been working for us outside over the years. They’re trying to fill those shoes.”

Lawrence was a key addition to the 2012 recruiting class. He committed in December after finishing his freshman season at Butler (Kansas) with 66 tackles, 27 tackles for loss and 10 sacks. He chose Boise State over Tennessee, South Florida, Kansas State and Mississippi.

“He’s physical — really strong,” defensive coordinator Pete Kwiatkowski said. “He’s just a good ol’ hard-nosed player.”

Lawrence and Ukwuachu played the same end position in spring ball, the “stud” position that was McClellin’s home.

Coaches moved Lawrence to the other side — a more traditional end spot — for fall camp.

“During spring, we helped each other out,” Ukwuachu said. “We try to push each other as much as we can. We’re both not prototypical size for a defensive end. We have to use our quickness for an advantage.”

That’s particularly true for Ukwuachu, whose role includes playing like a linebacker at times — rushing from a stand-up position and dropping into coverage, the skills that made McClellin so versatile.

The Chicago Bears drafted McClellin in the first round of the NFL Draft in April.

“I watched him every day in film,” Ukwuachu said. “He was one of the smartest D-linemen I’ve ever been around. He knows where to strike. I’m trying to emulate what he does and use my quickness to my advantage like he did.”

Said Kwiatkowski: “Hopefully we can get (Ukwuachu) playing like the guy who played that position last year.”

Ukwuachu’s biggest challenge might be his size. He has grown from 203 pounds to as high as 230 but will face linemen who are around 300 pounds all season.

His keys to success: “Basically, just eat, eat, eat, eat,” Ukwuachu said. “Try to get up there weight-wise. Other than that, being physical. I’ve got to practice being more physical.”

Ukwuachu, whose parents moved to America from Nigeria in the 1980s, also played wide receiver at Pearland (Texas) High.

He chose Boise State over a dozen other schools because of the bond he formed with the coaches. He was the second commitment in the 2011 recruiting class, behind only quarterback Jimmy Laughrea. Ukwuachu’s short list included Illinois and Louisville.

“Most schools didn’t want to take a risk on me because of my size,” he said. “Boise State had faith in me. Plus, they’re a powerhouse — that helped a little, too.”

Now Ukwuachu has a chance to reward that faith.

“He’s lanky, he’s very athletic, he’s got great change of direction,” defensive line coach Andy Avalos said. “He’s got a lot of attributes that we love about him. If he’s got the right mind-set, to come to work every day and get better and focus on the details, he’s going to be a good player.”

Chadd Cripe: 377-6398, Twitter: @IDS_BroncoBeat