http://www.sbnation.com/college-football/2014/4/21/5630688/boise-state-football-2014-preview-schedule-roster
As you can see, there's been some regression the past few years:
"The most underrated aspect of Boise State's elite teams was the defense. Players like Kellen Moore and Ian Johnson got the headlines, but Boise State ranked in the Def. F/+ top 20 every year between 2008 and 2012. The Broncos even ranked first in 2010.
The shine came off in 2013. Boise State still had a decent mid-major D, but you have to add the "mid-major" distinction. Good offenses tore the Broncos apart: Washington averaged 7.0 yards per play, Fresno State averaged 6.2, and Oregon State averaged 6.8. Even BYU (6.2) and Colorado State (5.7) had some success."
...
"So no, Boise State probably won't threaten to crack the top 10 this year. But the Broncos still have loads of experience and a wealth of young play-makers, and considering the losses at Fresno State (on offense) and Utah State (on defense), they probably have more known, proven entities than any school in the conference. Harsin has proven himself in each step of his career, and I really do love the premium he seemed to put on both young energy and local ties when putting his staff together.
Boise State should be able to run the ball, and the Broncos should once again have too much on defense for most Mountain West opponents. They probably won't have enough to beat Ole Miss in Atlanta to start the season, but with Fresno State and Utah State coming to play on the blue field, they are pretty clearly the conference favorite to me in 2014."