Here are five things we learned about the Trojans:
Defensive breakdown in final moments
Coaches talk about being prepared for any situation -- and USC might have prepared for a Hail Mary pass -- but there was a communication breakdown in the final seconds.
Some players did not know what defense they were supposed to be using on the final play, when Arizona State quarterback Mike Bercovici heaved the pass toward the end zone.
Safety Gerald Bowman said coaches made a call and then switched it.
"I don't think everyone was on the same page," he said.
Linebacker Hayes Pullard, who was in position to defend the Hail Mary, said he did not know where he was supposed to be on the play.
"I can't say I do," said Pullard when asked if he knew the final play call.
USC defensive coordinator Justin Wilcox said the call was switched because coaches did not know if Arizona State would try to set up a field-goal attempt or throw a Hail Mary.
Wilcox indicated that players did not look to the sideline to check the defensive call.
Defense's identity is a mystery
Two games after they gave up 452 rushing yards to Boston College, the Trojans gave up 510 passing yards against an Arizona State team led by a quarterback making his second start.
USC had not surrendered a passing touchdown this season, but Bercovici threw five against the Trojans.
And USC could not slow Sun Devils receiver Jaelen Strong, who caught 10 passes for 202 yards and three touchdowns.
Where's the line
USC's front seven was touted before the season as one of the best in college football.
Five games into the season, the defensive line is struggling.
It did not happen against the Sun Devils.
Bercovici completed 27 of 45 passes for 510 yards and five touchdowns. He was rarely under duress and was only sacked twice — both times by USC linebackers.
Simmons made four tackles, Woods had two. Pelon did not record a tackle.
Woods, Pelon and Simmons have yet to record a sack.
Leonard Williams, who Sarkisian said had been playing to standards, made three tackles against Arizona State. Williams has 30 tackles, including two sacks, and has intercepted a pass this season.
USC does not have a backup snapper
USC long snapper Zach Smith was sidelined because of a concussion suffered in last week’s victory over
Peter McBride started in his place but Sarkisian quickly abandoned the option.
In USC's first fourth-down situation, Sarkisian opted to have quarterback Cody Kessler punt.
Punter Kris Albarado handled the next two kicks, but McBride was called for a false-start penalty.
Sarkisian had Kessler punt the rest of the game.
"We didn't feel great about the operation of our normal punting team," Sarkisian said. "We went with a spread punt with Cody and we felt that gave us the best chance."
Kessler punted four times.
College Football Playoff even more of a longshot
Some said USC was never a College Football Playoff contender, but the Trojans did have a shot after defeating Oregon State to improve its record to 3-1.
But now with two losses...
If there is still a glimmer of hope, it is that every
USC plays at Arizona on Saturday. A Trojans victory would keep USC in play to win the Pac-12 South division.