Posted by ESPN.com's Ted Miller

While one major theme going into the 2009 season might be USC's vulnerability, that won't center on the offensive line.

Get it? "Center" on the offensive line! Please, stop. Oh, thank you. Thank you. No stop clapping. Seriously.

The Trojans are positively stacked up front. All five starters are back -- including two All-Pac-10 performers -- and a couple of those guys will be challenged this spring by talented underclassmen.

Everyone else in the conference has questions on the O-line, though no one would qualify as completely rebuilding.

The problem here is this: The lines that struggled most last year -- UCLA, Arizona State and Washington State -- have the most returning experience.

That's the peril of returning starters being the be-all, end-all of evaluation: Will that youth blossom with experience? Or were those guys just bad?

Here's a look.

Great shape

• USC: The Trojans will be on most preseason "Nation's Best Offensive Line" lists. Center Kristofer O'Dowd, a two-year starter and leading Remington Award candidate, and sixth-year senior Jeff Byers will lead the charge. And there are hungry youngsters looking to make a statement.

Good Shape

• California: There's a lot of "we'll see" here, too. Two All-Pac-10 performers -- All-American center Alex Mack and guard Noris Malele -- are gone, as is outstanding line coach Jim Michalczik. Still, seven guys return who own starting experience.

• Stanford: Three starters are back, led by tackle Chris Marinelli, from one of the conference's most physical offensive lines. The down side is the departed guys, center Alex Fletcher and tackle Ben Muth, were the best and most physical of the bunch.

• Oregon State: The Beavers welcome back 2 1/2 starters, the 1/2 being tackle Mike Remmers, who capably filled in while Tavita Thompson served a suspension. Alex Linnenkohl might be second only to O'Dowd at center, and position coach Mike Cavanaugh will coach up his young guys.

• Arizona: Two starters are back, but that doesn't include center Blake Kerley, who will sit out spring while recovering from the knee injury that ended his 2008 season, nor Adam Grant, who began the 2008 season as the starting tackle.

We'll see

• Oregon: The Ducks lost four starters from a dominating offensive line, but four return with starting experience: Bo Thran, Jordan Holmes, Mark Asper and C.E. Kaiser. Still, this will be an area to watch this spring.

• Arizona State: Basically, everyone on the depth chart, other than guard Paul Fanaika is back. But count on the coaches moving guys around and looking at a variety of combination to fix what has been a two-year Achilles heel.

• UCLA: Much like ASU, UCLA returns nearly everyone from a line that got whipped in 2008. But some new guys -- transfers, players returning from injury, incoming freshmen -- should make spring (and then fall) highly competitive, particularly with a pair of projected starters, guard Darius Savage (ankle) and tackle Mike Harris (foot), sitting out.

• Washington: Three starters are back from a line that underachieved last year -- heading into 2008 most projected the O-line being a Huskies strength. Expect new line coach Dan Cozzetto, not known as a soft touch, to be particularly fiery with this crew.

• Washington State: With four returning starters -- and three others with starting experience -- led by center Kenny Alfred, there's a chance for dramatic improvement here. The Cougars were forced to play young guys who weren't physically ready in 2008. They should be more ready in 2009.