The setup: After finishing off the last of their away games, the road-weary Trojans returned to the Coliseum in hopes of solidifying their standing in the Pac-10.

The story: Stanford made itself at home on homecoming day for USC by running roughshod over the Trojans in a 55-21 blowout. The 34-point loss was the worst in the Coliseum in almost 43 years for USC.

Daily Trojan | Mannat Saini

“I’m not sure I have the right words to describe being humbled like this,”

Stanford racked up 325 yards rushing and was led by senior running back Toby Gerhart, who tallied 178 yards and three touchdowns. The Norco, Calif., product was only recruited as a fullback and linebacker by USC coaches, who believed he would not be able to be a running back in the Pac-10.

But Gerhart ran through the heart of the Trojan defense all day behind Stanford’s gritty offensive line. The Cardinal repeatedly utilized the power play, as coaches and players called it, to get Gerhart moving downhill.

Stanford’s offensive success was all the more startling given the few number of surprises they offered.

“They ran the same plays we thought they were going to run,” senior safety Taylor Mays said.

Saturday’s outcome was the latest in a frustrating series for USC’s maligned defense. Last week’s performance against Arizona State gave the Trojans reason for confidence, but Carroll said that he did not think his team had solved its glaring errors.

“We’ve just fallen apart here and given our opponents the chance to do whatever they want,” he said.

Barkley’s struggles: True freshman quarterback Matt Barkley threw a career-high three interceptions and fumbled once against the Cardinal.

With wide receiver Damian Williams sidelined by ankle injury, Barkley finished with fewer than 200 passing yards for the third straight game.

The recent woes perplexed the signal-caller, who said he would have to look at film to determine the source of his struggles.

“I don’t feel flustered,” Barkley said. “We’ve had some bad breaks. When we’re turning the ball over like this, it’s tough to bounce back.”

Barkley’s most costly mistake came when a pass intended for Brice Butler was intercepted by Stanford cornerback Richard Sherman, who then streaked 43 yards down the sideline for a touchdown. The score gave Stanford a decisive 42-21 lead with less than 12 minutes remaining in the fourth quarter.

“He looked like a kid,” Sherman said. “He’s a great quarterback and he’s going to make great plays, but everybody has to grow.”

The call: Stanford coach Jim Harbaugh surprised many with a fourth-quarter decision to attempt a two-point conversion with the game well in-hand after Gerhart’s third touchdown put the Cardinal up 48-21. Gerhart was stopped short of the goal line, but Harbaugh’s move still drew plenty of questions following the game.

“I think he was trying to go for 50,” Gerhart said with a smile.

Carroll said he was not offended by the decision and did not address it in the postgame handshake.

“In that situation, they can do whatever they want,” Carroll said. “Sometimes those decisions are for attitude and your own team, so you do what you have to do.”

The decision did grate some USC players, however.

“It was kind of dispectful,” junior linebacker Malcolm Smith said. “It was definitely a punch in the face.”

Insult to injury: Mays’ postgame press conference was drowned out by the sounds of Stanford hollering and knocking against their lockers, rattling the wall.

“They deserve to have that feeling,” Mays said.