Stanford defeated No. 6 USC, 41-31, on Saturday evening at the Coliseum. Here are five things we learned from the game.Nonconference scheduleUSC became an honorary member of the Sun Belt Conference to open the 2015 season and the easy schedule did the Trojans no favors.USC routed Arkansas State, 55-6, in an opener and followed with a 59-9 victory over Idaho.The blowout victories provided a false sense of confidence.The Trojans deserved credit for beating the Red Wolves and Vandals decisively, but the non-conference games left plenty of questions about whether the team was ready for Pac-12 competition.Clearly, the defense was not.Defensive woes USC hardly put pressure on Stanford quarterback Kevin Hogan and the fifth-year senior capitalized on it.Hogan completed 18 of 23 passes for 279 yards and two touchdowns. He rushed for 28 yards in seven carries.USC sacked Hogan once in the first half and the Trojans appeared to make halftime adjustments which led to two sacks to start the third quarter.But that pressure wasn't enough.Hogan had plenty of time to pick apart USC's secondary and complete passes to nine receivers.He converted eight of 12 third-down situations.Offense is readyThere is room to improve for USC's offense.It converted only four of 10 third-down situations.However, the offense hardly was at fault for the loss to the Cardinal.Quarterback Cody Kessler completed 25 of 32 passes for 272 yards and three touchdowns.Tailback Tre Madden rushed for 64 yards and a touchdown in nine carries and Justin Davis rushed for 46 yards in eight carries.And the line protected Kessler, who only took one sack.Penalties add upUSC committed eight penalties for 87 yards against Stanford and several of them were personal fouls.Coach Steve Sarkisian said after the game that those penalties were uncharacteristic for his team, but the penalty numbers have steadily grown over the last three games.The Trojans committed three penalties for 25 yards against Arkansas State and six for 67 yards against Idaho.Adoree' Jackson missing on offenseSophomore standout Adoree' Jackson didn't mince words after the game.He thought he would play more on offense.Jackson did not make a catch.On defense, the ball was seldom thrown toward the cornerback's side of the field. He made five tackles.Jackson made his biggest impact on special teams.He returned five kickoffs for 118 yards.He also returned a kickoff 97 yards for a touchdown, but it was called back because of a penalty.Questions or comments about USC? Email me at LNThiry@gmail.com or tweet @LindseyThiry and I will respond to select messages in a weekly USC Now mailbag.