San Diego • By the level of “boos” anytime BYU walked on the field or did anything worth celebrating, it was clear San Diego State fans really don’t like the Cougars.

It could be in part because the Cougars routinely beat the Aztecs during the team's old WAC and Mountain West rivalry days. Whatever the reason, one thing was clear: SDSU didn't want to lose to BYU again.

And the Aztecs didn’t. SDSU’s defense — one of the best in the nation — kept BYU to its lowest-scoring game of the season on the way to a 13-3 win.

The loss snapped a five-game winning streak the Cougars went on since losing three straight, including disappointing losses to Toledo and South Florida. BYU has not won six in a row in one regular season since 2008.

“It’s disappointing to lose in general — not fun to lose,” linebacker Isaiah Kaufusi said. “We had some really frustrating loses this year at Toledo and South Florida, but all four of the loses previous to this one were frustrating. So, this one’s about the same.”

The defense wasn't the only thing working for the Aztecs, whose offense was led by a rookie.

Redshirt freshman Carson Baker hadn’t even taken his first collegiate snaps yet and recorded his first start Saturday. Season starter Ryan Agnew was sidelined with a calf injury that was aggravated in last week’s loss to Hawaii.

Baker threw for 172 yards and one touchdown on 19 of 24 passing.

While the Cougars scored first on a 24-yard field goal by Skyler Southam toward the end of the first quarter, SDSU took the lead with 13 seconds remaining in the first half with a 25-yard reception by Daniel Bellinger.

Defensive lineman Khyiris Tonga said the Aztecs’ touchdown was a result of miscommunication in the backfield.

“We knew our little mistakes cost us,” Tonga said. “We gave up a cheap one right before the half — and that’s on us as a defense.”

But other than SDSU's final drive of the first half, the Cougar defense was pretty sound.

The Aztecs added a field goal in both the third and fourth quarter, while preventing the Cougars to score again.

However, it wasn't all on SDSU. BYU had plenty of missed opportunities (like the two missed field goal attempts), unfortunate penalties and costly turnovers.

BYU quarterback Zach Wilson believed the loss lies with the offense. The defense gave up the second-lowest amount of points of the season, which should have led to a win, but the offense should have been able to finish.

Wilson had the third 300-yard game of his career with 316 yards, which put him at 2,108 yards for the season, but he was also intercepted twice.

The sophomore said the biggest problem was that he had a lot of off-balance throws and small-pocket situations. He has to make better throws off platform.

“It was mostly just trying to make a play out there,” Wilson said. “A lot of balls got tipped. They got a lot of hands on balls and back on my throwing motion. You know, I hit the ball on a guy a couple of times and the ball flutters in the air. They did a good job of bringing the aggressive pass rush.”

The Cougars finished with a total of 416 yards while holding SDSU to 269 total yards and had 23 first downs to the Aztecs’ 12, and yet weren’t able to close out the game.

“Defensively, I thought the guys did well and the only thing we could have done to win the game was shut them out,” BYU coach Kalani Sitake said. “That's what it would have taken. And get some turnovers. San Diego State took care of the ball and were mindful of it and didn't take a lot of risks and we weren't able to capitalize on it.

“We’ve just got to go back and get back to work.”