Watching UCLA at Oregon last night, it was hard to tell how good Oregon's D is.  No doubt, they did the job. But they were facing one of the most inept offenses in all of CFB...and they did not look dominant to me.  In blowing out UCLA, Oregon gave up more yards passing than any UCLA opponent had all year long (159 yards), and they gave up 19 first downs...14 of which came in the first 2 1/2 quarters of the game.  By comparison, Cal and Stanford held UCLA to 13 and 15 first downs all game, respectively.  Oregon's D certainly didn't look as strong as USC's D did against Cal...a team which actually has some playmakers and experience on offense. But that's just one game. Looking at total yardage allowed over the season, Oregon would seem to have a substantial defensive advantage over USC:

Oregon's D rank:  32nd, 332 yards/game  (rushing - 35th, passing - 50th)

USC's D rank:    86th, 398 yards/game (rushing - 36th, passing - 106th)

However, if you look a little further, 5 of Oregon's 7 games have come against offenses ranked 86th or lower.  WSU is statistically the 3rd best offense that Oregon has faced.  In comparison, the Cougars are the distant 7th (worst) offensive team that USC had faced.  These are the offensive rankings of each team's opponents:

Oregon:  12, 20, 86, 97, 103, 104, NA (Portland St., a 2-4 1aa team)

USC:    11,12, 46, 58, 60, 62, 86

So if we ackowledge that Oregon can play D against teams like WSU, Tenn, UCLA, New Mexico, and Portland State, how do they fare when facing an offense ranked better than 86th?  Answer:  They've been shredded.  Against ASU (ranked 20th in total offense), Oregon surrendered 578 total yards, 387 yards passing, 31 first downs, and 31 points.  Against Stanford (ranked 12th in total offense), Oregon surrendered 518 total yards, 341 yardes passing, 25 first downs, and 31 points.  These are bascially the same kind of numbers that USC's D has allowed when facing similar quality offenses.  And if you look at common opponents, both Oregon and USC have played Stanford at home and WSU on the road.  It's astonishing how similar the combined defensive statistics are for the two defenses:

USC D (2 game total):      1st downs:  47,  Tot yds:  801,  Run yds:  260,  Pass yds:  541,  Tot points:  53

Oregon D (2 game total):  1st downs:  46,  Tot yds:  854,  Run yds:  268,  Pass yds:  586,  Tot points:  54

I think if you throw out how Oregon's D has played against bottom-feeder offenses, and focus on how they have played against good offenses, and against common opponents with USC, there isn't any compelling reason to believe that Oregon's D is any better than USC's.  In fact, if USC's D is really improving, it may even be substantially better than Oregon's D.  Of course, that doesn't necessarily mean that USC will have any advantage in a shootout.  Statistics rarely telll the whole story, but they do suggest that it will be a wild game in the Coliseum next week.

Trojans Fight On!