The Trojans fell out of the rankings after a 32-31 loss to Washington last week. Yet that loss was by no means the only reason for USC's slide. Even in victory, the Trojans haven't been impressive.
They struggled to beat a Hawaii team that was blown out by Colorado and needed a last-play field goal to beat Army. Lackluster victories over mediocre Virginia and Minnesota and a rout of hapless Washington State followed.
Defense has been the big problem. The Trojans are allowing 418.8 yards per game to rank 99th in the nation in total defense. They're 116th against the pass and have allowed 10 touchdown passes.
"I don't think we tackled very well, especially in the secondary," first-year coach Lane Kiffin said. "We're still in the thinking process instead of playing really fast."
Defense isn't the Trojans only issue, though. They've committed nine turnovers, they're among the most-penalized teams in the nation and the kicking game is suspect.
USC lost four conference games last season, the most since 2000. They could be in danger of losing at least that many this season. Three ranked nationally ranked opponents remain on the schedule: Oregon, Arizona and Stanford, which plays host to USC on Saturday.
"The conference being so deep, you've got to come ready to play every week," Kiffin said. "We're getting ready to play a great team, a physical team in all phases of the game.
"This is not the old SC. You're looking at a team that was 5-4 in conference last year and is 1-1 this year. We're going to have a lot of close games that we have to win in the fourth quarter."
Stanford coach Jim Harbaugh, whose Cardinal blasted the Trojans 55-21 last season, warned not to overlook USC. "USC is still a very powerful team," he said.
That could be dismissed as coach-speak. Coaches typically praise other teams, especially those they're about to play. But USC does have talented sophomore quarterback Matt Barkley, a deep group of running backs headed by Allen Bradford and a big-play threat in wide receiver Ronald Johnson.
Still, unless major improvement is made in a number of areas it is possible - maybe even likely - that USC could end this season unranked for the first time since 2001.
By the way, that's the last year South Carolina finished in the top 25.
Best matchup: UCLA at California. Cal has held three of its four opponents to fewer than 100 rushing yards. But the Bears gave up 316 yards when facing Nevada's "Pistol" formation. The Bears are facing UCLA, which is 10th in the nation in rushing offense and also uses the "Pistol." Can the Bears make adjustments and more effectively defend against the "Pistol" this time? Or will Bruins RB Johnathan Franklin post a fourth consecutive 100-yard game and QB Kevin Prince run for big gains? The answers to those questions likely will decide the outcome. Cal's defense figures to get a boost with the return of LB Mike Mohamed from injury. He did not play against Nevada.
Player on the spot: Arizona State LB Vontaze Burfict. His spot is on the bench, at least for the start of the game. Sun Devils coach Dennis Erickson announced Burfict would not be in the starting lineup for Saturday's game against Washington as punishment for head-butting Oregon State QB Ryan Katz last week. Gerald Munns will start in place of Burfict, an extremely talented sophomore who has a history of committing personal fouls. Burfict is Arizona State's leading tackler and will play against the Huskies, but Erickson said he would be held out longer if he continues to draw penalties.
Numbers game: Oregon State is ranked just 99th in the nation in total offense, but the Beavers are probably better than that. Many teams' stats are skewed after facing weak early-season opponents. That's not the case for the Beavers. They've faced Boise State, which leads the nation in total defense, and TCU, which is third in that category. This week, Oregon State faces Arizona, which is second in total defense. Their other two opponents were Arizona State, which is ranked 54th, and Louisville, which is ranked 62nd.
What they're saying
"It's a top-10 team. Nothing new." - Oregon State DT Stephen Paea, on facing Arizona, the third top-10 team the Beavers have faced this season
"If you do have to tell a Heisman voter who the good players in the country are, maybe they shouldn't be voting." - Oregon coach Chip Kelly, to the Eugene (Ore.) Register-Guard, on why Oregon, which once paid thousands to put a huge billboard of Ducks QB Joey Harrington in New York's Times Square, won't have a similar campaign for RB LaMichael James
"I think Oregon can put 52 on the New York Giants." - USC's Kiffin, on Oregon's explosive offense
Etc.: Arizona WR Juron Criner, who has been slowed by turf toe, and FB Taimi Tutogi, who is overcoming a sprained knee, have returned to practice and expect to start against Oregon State. ... Arizona State is tied for 107th in the nation with just five sacks. ... Sun Devils P Trevor Hankins has had 19 punts with 12 covering 50 yards or more. ... Oregon has rolled up more than 600 yards in offense in three of its five games. ... Oregon's James has exceeded 100 rushing yards in 11 consecutive regular-season games. ... Stanford WR Chris Owusu's status for this week's game against USC is uncertain. Owusu was knocked out of last week's game against Oregon on an apparent helmet-to-helmet hit. ... UCLA's Prince sat out last week's win over Washington State, but is ready to play this week against Cal. But WR Nelson Rosario, the Bruins' leading receiver, is doubtful because of a sprained ankle. ... USC senior RB Allen Bradford's career-high 223 rushing yards in last week's game against Washington was the most ever for a USC player in a loss. ... Washington has won both games this season in which RB Chris Polk has rushed for 100 yards. ... Washington State QB Jeff Tuel has passed for 200 yards in each of the Cougars' five games. ... Oregon has allowed just seven points in the second half this season, and the Ducks have outscored opponents 114-7 after halftime. ... Stanford K Nate Whitaker has converted all nine of his field-goal attempts this season. Going back to last season, he's hit 14 in a row. ... UCLA is ranked 10th in the nation in rushing offense at 262.4 yards per game. Last season, the Bruins ranked 97th (114.6 ypg). In '08, they ranked 116th (82.8 yards per game).
Olin Buchanan is the senior college football writer for Rivals.com. He can be reached at firstname.lastname@example.org.