Jason Shirley doesn't mind admitting it now. The defensive line was a huge factor in Fresno State's struggles last season.

"Last year's trouble was the defensive line wasn't as strong as it was in past years," said Shirley, now a senior and entering his third season as the starting nose tackle. "If we're going to be weak, the defense is going to be weak. And that's what we had last year -- a weak defense."

Fresno State ranked in the bottom half of the nation in nearly every defensive category, including 97th in points allowed per game (28.3) and 108th in third-down defense.

The Bulldogs' solution to their problem: Get better on the line and everything else will fall into place.

"We start it all," Shirley said. "We are the first line of defense. When we're playing awesome, everyone else usually does, too.

"If we get pressure on the quarterback, [defensive backs] usually get picks. If we pressure through the offensive line, the linebackers get lanes to run through. If we get big hits, we make big plays. We've got the talent to do that."

But getting this Bulldogs unit to actually perform at a high level isn't so easy.

The line lacks a fast pass rusher on the edge.

Hence, coach Pat Hill's cry for junior Jason Roberts to produce. The former Central High standout has yet to live up to his high school hype when he drew comparisons to Miami Dolphins defensive end Jason Taylor and turned down the Bulldogs to go to Washington State, where he redshirted for one season before transferring to Fresno State.

The 6-foot-5, 280-pound Roberts -- one of, if not the Bulldogs' fastest defensive lineman -- had just 10 tackles in 11 games last season.

Fresno State has not had a player finish with double-digit sacks since 2003, when Brian Morris nabbed 11.

The defensive line also lacks size. Take away the 6-foot-5, 335-pound Shirley, and the Bulldogs have no one who weighs more 300 pounds.

Last year's defense ranked 86th in pass defense at 222.2 yards allowed and 67th against the run at 140.8 yards.

But what the unit has going for it is much like the rest of the team -- a desire to prove they can.

Can Shirley play at a dominant level on a consistent basis or will he continue to show only glimpses of his potential on a limited number of plays?

Can senior defensive end Tyler Clutts rise to the occasion with offenses paying more attention to him?

Can undersized defensive tackles Jon Monga, Charles Tolbert and Ikenna Ike hold their own against the run?

But most importantly to a Bulldogs turnaround, can the defensive line play at a highly physical level and work together?

"Too early to say," defensive line coach Kerry Locklin said. "We've got to work on our timing, cohesion, which guys work best together.

"There's a lot of guys who've got to step up. Much is given, so much is expected."