Southern California's latest loss to a huge underdog shouldn't shock anyone. These "stunning" upsets are practically an annual tradition for the Trojans.

Yes, USC's cup runneth over with NFL prototypes, flashy athletes and the most physically gifted group of college football players in the country.

Yet, still, the Trojans lost to 25-point underdog Oregon State on Thursday night. And to 41-point underdog Stanford last season. And to double-digit underdog UCLA in 2006 with a shot to play in the national title game on the line — just five games after their first "shocking" loss in Corvallis, Ore.

Once is a fluke. Twice, well, blame John David Booty. Now, it's a trend.

What in the name of Reggie Bush is going on with these Trojans?

"It's all mental," said former Auburn coach Terry Bowden, son of Florida State's Bobby Bowden. "It's all kids believing they don't have to do their best.

"One of the lessons my old man taught me, he said, 'One thing you've got to remember is you can't get 'em up every week. You better have them fundamentally sound, able to block and tackle, because some days you can't get 'em ready to play."

The lessons of last season clearly weren't learned by USC — or those who cover college football. After crushing Ohio State two weeks ago, this USC team was anointed as perhaps the greatest of them all, a lock to play for a national championship in Miami.

"We're so quick to jump on the bandwagon," Trev Alberts, the former Nebraska star, now an analyst for CBS College Sports, said in a telephone interview Friday. "Maybe we thought a little too much of USC."

With 10 games left in USC's season, the only question remaining was: Who's going to play the Trojans for the national title?

Surely, Carroll told his team this was nonsense. That the real season, Pac-10 play, started Thursday night.

Yet his team played as if Oregon State (2-2) were of no concern. As if the mere sight of Rey Maualuga, Brian Cushing, Mark Sanchez and Joe McKnight would be enough to make the Beavers buckle.

Instead, little freshman running back Jacquizz Rodgers spent the first half pin-balling off the mighty Trojans (2-1). By the time USC realized it had to get serious it was 21-0 Oregon State.

"It almost looked like they were going through the motions," Alberts said. "(The USC coaches) didn't have their team ready to play."

USC's second-half comeback fell short because Sanchez looked a lot like a quarterback starting for only the sixth time in college. Because the offensive line with four new starters played very much like an offensive line with four new starters. Because McKnight seems so badly to want to be the next Reggie Bush, he's passing up 3-yard gains and dancing into 3-yard losses.

"We weren't ready to do what we needed to do," Carroll said after the game. "We felt like we had great preparation. We thought we did everything like we needed to and then when we're out there it just didn't feel like it."

Bowden, an analyst for Westwood One Radio and YahooSports, said by phone that USC has become a victim of its own high standards.

No team is above a letdown, "but we recognize it in (USC) more than others," Bowden said.

In the last six seasons, USC is 72-9, with two national titles and one near miss courtesy of Vince Young and Texas. The Trojans have played in six straight BCS games and won five, usually in impressive fashion.

But the recent losses have been as puzzling as the victories have been spectacular.

The latest one will produce a new No. 1 team. No. 2 Oklahoma and No. 3 Georgia are next in line. The Sooners host TCU on Saturday. The Bulldogs have the first of several huge SEC games against No. 8 Alabama.

USC's loss was no doubt celebrated all over the country, from Gainesville, Fla., to Columbia, Mo., by teams with national title aspirations.

The Trojans now move toward the back of the line among championship contenders, forced to hope the upset bug that hit them becomes an outbreak as it did last year, spreading to the Big 12 and Southeastern Conference.

September losses can be overcome, but USC doesn't have another current Top-25 team on its schedule. Pollsters might not be so quick to give the Trojans the benefit of the doubt if it comes down to them and a one-loss team from the SEC or Big 12 for a shot at the national title — no matter how many five-star recruits they have.