The stats don't lie — Tennessee's defense was horrendous a year ago.

The Vols finished 107th in the FBS in points against per game (35.7) and dead last in the Southeastern Conference. They also gave up 50 more yards per game than any other SEC school.

That same unit is returning most of its starters from 2012. So, why should 2013 be any different?

According to Vols coaches and players, it is the scheme. After running the 3-4 up front last season under then-defensive coordinator Sal Sunseri, they are moving back to the more traditional, familiar 4-3 scheme.

New head coach Butch Jones immediately announced the switch upon his arrival in December 2012, and leaders like senior defensive end Jacques Smith have embraced the move back.

"We are all experienced in this system," Smith said. "After all, we were 27th in the country the last time we played the 4-3 defense."

Smith is referring to 2011, when a lackluster offense was more to blame for the Vols' 5-7 finish than a defense that only allowed 22.6 points per contest. Those Vols gave up a combined 34 points to division rivals South Carolina and Georgia, as compared to 89 in those two contests last season.

After losing Tyler Bray, Justin Hunter, Cordarrelle Patterson and Mychal Rivera to the NFL this past offseason, a defensive effort similar to 2011 may be needed for the Vols to qualify for a bowl.

Perhaps the biggest cog in that defense will be defensive tackle Daniel McCullers. The 6-foot-8, 351-pound menace was the centerpiece of the Vols' 3-4 last season, which excited fans but ultimately diminished his overall impact.

"With a 3-4 defense, I had to take on blockers for the linebackers and in the 4-3, we have a lot more opportunity to make plays," McCullers said. "The 4-3 is more of a pass rush and making more plays and getting penetration.

"As a D-line, we have a lot of good players who can run the 4-3, so we're going to continue to work."

McCullers finished with a productive 39 tackles and 5.5 for loss in 2012, but he struggled to be an every-down player. But he said so far, so good as far as his fitness goes in 2013.

"Training-wise, we've been grinding since the summer and I've been shedding the weight down," McCullers said. "My body has changed, and I've gotten in better shape to where I can go a lot more plays without getting winded. We're going to keep working."

The linebacking crew boasts an unfamiliar feeling of experience this year. Juniors A.J. Johnson and Curt Maggitt have started since they were true freshman, and senior Dontavis Sapp has finally settled into a starting spot after tussling for playing time in recent seasons.

Sapp was not shy about bragging on his teammate Johnson, who led the SEC in tackles a season ago.

"A.J. is an All-American, All-SEC preseason, but he comes like he's still fighting for a starting spot," Sapp said.

With Maggitt still working his way back from a torn ACL he suffered against Missouri late last season, Brent Brewer has asserted himself in the third and final spot for the season opener against Austin Peay.

After switching from safety, a reasonable concern remains if Brewer has the physicality to move up to situations like covering the run and rushing the passer. But Sapp was quick to oust that belief.

"Brent's as strong as an ox," Sapp said. "He's old, but he's still strong. He'll come down and hit you. If he doesn't do anything else, he's going to hit you.

"He's adjusted well, probably better than most would think from moving from a safety. He's actually come on pretty fast."

The Vols' defensive end spot will be thin early on as Smith and impact freshman Corey Vereen will miss time with training-camp injuries. But McCullers is not worried about the pass rushers to his side.

"We aren't really too much focused on (the injuries) because we have guys who can step up," McCullers said. "They're going to have to work harder and learn the system and we'll take them under our wings."