Matt Barkley said it was not acceptable.
Coach Pete Carroll, somewhat surprisingly, agreed.
Barkley, the first true freshman to start at quarterback for USC under Carroll, goes into Saturday's regular-season finale against Arizona with 12 touchdown passes and 11 interceptions in 10 games.
"Compared to how many touchdowns I've thrown and how many attempts I have, it's not acceptable," Barkley said Tuesday of the interceptions. "I've struggled here or there, but I think I've made great strides in different areas."
Barkley was still enjoying the afterglow of the Trojans' 28-7 victory over UCLA, a game he punctuated with a controversial 48-yard touchdown pass to receiver Damian Williams in the final minute.
"That's what is fresh in my mind," Barkley said. "Winning like that and in that fashion just made it for me."
Barkley's season has included several highlights, including an impressive fourth-quarter drive at Ohio State and victories at California and Notre Dame.
But Barkley also struggled during much of the second half of the season.
"I don't really know if it met expectations or not," Barkley said. "At the same time there are a lot of things I learned from this year that I know will be helpful in my career."
While Barkley accepted responsibility for his mistakes throughout the season, Carroll has gone out of his way to deflect blame from the quarterback, citing penalties, receivers running poor routes and questionable calls by officials.
But he acknowledged that Barkley's touchdown-to-interception ratio did not measure up to what had become customary for the Trojans the previous seven seasons.
"In terms of how we've seen it in the past, the numbers aren't at all like we'd like them to be," Carroll said.
Nevertheless, Carroll said Barkley "had nothing to do with" the blowout losses to Oregon or Stanford. This week, he said Williams was at fault for an interception against UCLA.
"I'm not trying to cover for him. I just think that's the truth," Carroll said. "There's been a couple balls he shouldn't have thrown but there hasn't been that many of them."
Barkley and the Trojans will benefit in the coming years from the 2009 experience, according to Carroll.
"I was hoping that we'd make it easier for him by running the ball really consistently and really well," Carroll said. "The running game has been OK, but our inability to convert on third down has really held us back and some of that is the quarterback.
"He's done great at his spot. We needed to do better around and in support of him."
Carroll defends sideline behavior
Carroll spent much of his weekly news conference addressing the Trojans' sideline behavior.
USC's celebration after the touchdown pass against UCLA incited Bruins players to leave their bench area and move across the field.
Carroll addressed the issue with his players, but said he would not discourage them from responding emotionally.
"Last year in the Rose Bowl, the officials told us at halftime if we continue to celebrate as much on the sidelines they were going to call a 15-yard penalty on us," Carroll said. "And I blew it because I wanted to make them call that penalty.
"I wish we would have done it so they would have called the penalty on us, so we could have gotten penalized for having too much fun. Because I don't understand that."
Carroll added that his program was "mindful in trying to make sure that we don't cross the boundaries that cause an issue, because we don't want to be any part of that. But we want to have a great time doing it, and we'll continue to find a way to do that."
Carroll acknowledged that certain actions could produce a lack of respect, citing penalties incurred by the Trojans this season at Notre Dame.
Kristofer O'Dowd will return to his starting role at center, so Jeff Byers will move back to left guard and Butch Lewis will play right guard. . . . Tailback Joe McKnight sat out for a second day because of a thigh bruise. Carroll said the junior's work in practice would probably be limited so that he can play against Arizona.