The Boise State football team began working toward the 2013 season opener last week with four-days-a-week winter workouts.

The roster has changed dramatically in the seven weeks since the MAACO Bowl Las Vegas win — 23 seniors have departed — but the core of the team is unchanged, junior nickel Corey Bell said.

“There’s a little bit of a different feeling in that there’s different people in the room, but the coaches do a good job of keeping that same attitude that our team has tried to keep over the years,” Bell said. “It’s the same idea — we know what we’re getting into, how hard we’re going to work.”

Said strength coach Tim Socha: “If you’re going to have a successful summer, you’ve got to have a good base in the winter and set things up. It’s 1A and 1B.”

Socha, who joined the staff in 2006, always looks for ways to tweak the strength and conditioning program so players don’t feel like they’re performing the same tasks repeatedly.

“We have some fundamental things we believe in and we stick to but everything else around that we want to change up so it has a different feel,” Socha said. “By the time (quarterback) Joe Southwick is a fifth-year senior, we don’t want him to go into the weight room going, ‘This is going to be the same thing I’ve done the last four years.’ Because you’re not going to work as hard.”

This year, one major change is the implementation of the “Bronco Excellence Challenge.” The players have been divided into teams and will compete in workouts, academics and community service.

It stresses unity, like the Bronco Olympics during fall camp, but it’s more serious.

“It’s less home-run derbies with the tennis racket and more 10-yard starts and heavy dumbbell holds,” Socha said. “… It’s more of an emphasis on competition across the board and getting them to know each other a little better. It will keep guys accountable through all aspects of our program.”

The offseason program is critical to a few key positions. The defensive line needs to add bulk, the linebackers are still fairly new to the program and playmakers need to develop at cornerback and tailback.

“These couple months are some of my favorite months,” said Bell, who hopes to add up to 10 pounds to his current weight of 205. “You get to get in there and get stronger and get bigger and build on what you had the year before. … You go into fall camp and hopefully it’s paid off and usually you can see a pretty big difference.”

On a broader scale, the Broncos hope to notice a change in their run defense. They allowed six 100-yard rushers last season — most notably 205 rushing yards and 279 yards from scrimmage to Las Vegas MVP Bishop Sankey of Washington.

The Broncos open Aug. 31 at Washington — a rematch with Sankey.

“It starts in the weight room,” defensive coordinator Pete Kwiatkowski said after the bowl game. “We’ve got to get bigger. We’ve got to get stronger. We’ve got to continue to improve on being a physical team on the line of scrimmage, to get off blocks and not let guys hold us. I’m talking about the D-line, linebackers and DBs.”

Said Socha: “We talked about it. It just goes with time and it just takes time to build the kids you want to build. At defensive end last year, we had Demarcus Lawrence who was a junior college transfer and a guy who was in the program for one year (Sam Ukwuachu) starting for us. Over time, those guys will get bigger and stronger. It doesn’t happen overnight. … That’s obviously a major emphasis for us this year.”

Similarly, the offensive line hopes to establish a more physical presence in the run game this year. The Broncos averaged 4.6 yards per carry in 2012 but lacked consistency.

Senior left tackle Charles Leno Jr., an All-Mountain West second-teamer who will be a third-year starter, hopes to set the tone.

“I want to finish more — finish blocks — and be more dominant out there,” he said.

Chadd Cripe: 377-6398, Twitter: @IDS_BroncoBeat