Plenty of teams in the non-Bowl Championship Series football conferences can score points.

Few can play high-end defense.

That’s what for years separated Utah, TCU and Boise State from the pack.

And in 2012, that’s what made the Utah State Aggies arguably the most impressive non-BCS team in the country.

No. 18 Utah State (10-2) will cap its historic season Dec. 15 at Bronco Stadium against Toledo (9-3) in the Famous IdahoPotato Bowl(2:30 p.m., ESPN).

The Aggies rank eighth in the nation in scoring defense (15.4 points per game) and haven’t allowed a first-quarter touchdown all season. They beat Louisiana Tech and San Jose State, two high-scoring WAC teams that spent time in the Top 25. They also lost at Big Ten champion Wisconsin on a missed field goal and at BYU by three points in defensive struggles.

“That was the next step,” senior cornerback Will Davis said. “You look at last year, we had definitely good players and our defense just wasn’t there. Something was missing. We were giving up too many points a game. If you want to be a Top 25 team you need a defense that can get you there. This year, our defense stepped up huge.”

The Aggies ranked 68th in the nation in scoring defense last year, at 27.9 points per game. They held three opponents to fewer than 20 points last year; they accomplished that nine times this year.

The improvement came in the first year under coordinator Dave Aranda, who joined the staff from Hawaii.

“The guy knows what he’s doing,” Davis said. “He put a lot of work into it. After the first few games is when we started to buy into what he says. Once we believed in him fully, that’s when our defense definitely soared.”

The result was a season Utah State fans won’t forget. The Aggies claimed their first outright conference title (WAC) since 1936, won a school-record 10 games, posted a school-record 6-0 home record, beat a ranked team on the road for the first time (Louisiana Tech) and cracked the Top 25 for the first time since 1978.

The key was the defense, which has allowed fewer points per game than it has in any season since 1963.

“It’s been fun to watch,” coach Gary Andersen said.

Aranda replaced Andersen, the former Utah defensive coordinator, as the defensive playcaller. Andersen decided to run the defense himself in 2011 to get more involved in games, but quickly realized he didn’t want the dual responsibilities of head coach and coordinator.

This year, Andersen not only turned over the defense to Aranda but attended the offensive staff meetings instead of the defensive meetings.

That doesn’t mean he isn’t involved.

On Thursday morning, Aranda and Andersen discussed Toledo’s pass protection.

“It’s always good to have that type of information just two doors down,” Aranda said. “He’s been a super asset.”

This wasn’t necessarily supposed to be a breakout defense for the Aggies. They lost their two best defensive players, linebackers Bobby Wagner (playing well for the Seattle Seahawks) and Kyle Gallagher, and faced question marks across the defensive line.

The line, though, has played well with a nine-man rotation in the 3-4 scheme. Freshman Kyler Fackrell and junior Jake Doughty made the All-WAC first team as the new standout linebackers. And Davis leads the nation in passes defended.

Plus, Aranda’s unconventional pass rush generated 39 sacks — eighth-most in the nation — from 16 guys. The Aggies often only rush four, but they make it difficult for the offense to identify which four.

“It took all of spring really — our best scrimmage in the spring was the spring game,” Aranda said of rebuilding the defense. “Right away in fall camp, you could see the improvement. … With Coach Andersen, the culture here and the expectation here is that you’re going to play great defense and that’s the standard. That’s a huge part of it, because the kids responded to it.”

Chadd Cripe: 377-6398, Twitter: @IDS_BroncoBeat