Then it got worse.
Mitch Mustain played the entire second half, but ran into the same issues at Barkley, a lack of protection and opportunities faced with a massive deficit.
Given the circumstances, it was a minor miracle that the Trojans even finished with 255 yards of offense in a 36-7 thumping at the hands of the struggling Beavers before 44,969 exhilarated fans on Saturday night.
"Obviously our offense was terrible," USC coach Lane Kiffin said. "You can't play like that on offense and beat anybody."
USC (7-4, 4-4 Pac-10) had six three-and-outs and had two turnovers. There were penalties and negative plays that led to 16 third downs, converting just four.
"There was no rhythm. They did a really good job and we helped them," Kiffin said.
Those issues were magnified by the loss of Barkley.
Mustain was 8 of 17 for 60 yards in relief, but coaches and teammates came to the senior's defense.
"You can't put a guy in a much worse situation," Kiffin said. "It was good for Mitch to experience, especially if he's going to be our quarterback next week."
"I'm not going to be mad at him," said running back C.J. Gable, who scored the lone USC touchdown on a 13-yard run in the third quarter. "He did what he had to do. I'm happy he came out with his head up. He did good today."
Barkley said he didn't know if he would be ready to start against Notre Dame, which could result in Mustain making his first-ever start as a Trojan on Senior Day.
"At this point, after this game, I'm hoping I get another shot at it," he said. "We'll see what happens but I'm prepared. I'm ready to go this week whatever happens."
Diagnosed with a high ankle sprain, Barkley hobbled back to the sideline in the last minute of the third quarter on crutches in a walking boot.
It was the end to the worst night of Barkley's young collegiate career, completing just 10 of 19 passes for 75 yards. The sophomore also threw a deep out intended for fullback Stanley Havili into double coverage where it was intercepted by cornerback Jordan Poyer and returned 65 yards for a touchdown.
"The first half was terrible. We didn't move the ball. It was not good," Barkley said.
The offensive line, which performed so well against the talented defenses of Arizona State and Arizona, was manhandled by underachieving Oregon State (5-5, 4-3 Pac-10) and mammoth defensive tackle Stephen Paea.
"We never got our rhythm going, we never really clicked as a unit and it showed," left tackle Matt Kalil said.
Asked to explain the performance by the line Kiffin said, "I don't know.
"I don't know that answer. It is surprising because the last two weeks they went versus two top-15 rush defenses and rushed for 187 and 202 and kept the quarterback up most of the day."
Those struggles and another magnificent effort by Beavers running back Jacquizz Rodgers extended the Trojans' losing streak to three at Reser. They have not won in the state of Oregon since 2005, a game later vacated by the NCAA.
"I think it goes back to practice this week," fullback Stanley Havili said. "We had a couple down practices and it translates."
"I think we took them lightly and I think that's what happens when you don't take a team seriously. They got us today," Kalil said.
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