NORMAN, Okla. -- When the University of Oklahoma's spring football practice begins Tuesday, much attention will be focused on the biggest guys, with good reason.

Conventional wisdom says all the pieces are in place for the Sooners to contend for the national championship. Simply find some offensive linemen to block for all those budding superstars, and they're on their way back.

Well, maybe.

OU must replace four starters on the line. And those budding superstars sure look like they're just waiting for blockers. But offensive coordinator Kevin Wilson has a word of caution.

Those budding superstars? Quarterback Rhett Bomar and tailback Adrian Peterson? Malcolm Kelly, Juaquin Iglesias and Manuel Johnson? They have not arrived.

"We do have some very good, proven, young skill players," Wilson said. "But all they are is good, young players. They're not great yet."

Don't misunderstand. The longtime offensive line coach certainly understands the importance of blockers. He's been the guy who developed the Sooners' lines _ sometimes maligned, sometimes praised _ for the last few years.

"Every year, your offense starts with what those guys can or can't do," Wilson said.

Now, Wilson has moved up to running the entire offense. And with a staff shuffle, he's no longer coaching the offensive line. The rebuilding or reloading job falls to newcomer James Patton, a Wilson protege.

But that's not the reason for Wilson's unconventional wisdom. It's this: He sees how close OU might be to returning to the elite level. And he believes the offensive skill players have to improve for OU to get there.

Bomar improved a lot as the 2005 season went along. Malcolm Kelly emerged as a go-to, big-play receiver. And Juaquin Iglesias and Manuel Johnson flashed signs of brilliance.

They've got plenty of room for growth.

And don't forget Peterson. Yeah, he was injured last year. Probably, that's the only reason he wasn't in the Heisman race for a second straight season. He's sure to be a leading candidate in 2006.

But Wilson noted Peterson can improve, too. A year ago, he didn't go through spring practice because he was rehabilitating after shoulder surgery.

Missed most of the summer, too.

"He's a big-time talent," Wilson said. "But he's still raw. He's got a lot of development he can do."

There are many other priorities, of course. Although OU returns the bulk of a young team, questions must be answered.

J.D. Runnels is gone. Will a fullback emerge? What about a tight end? Defensively, OU must find replacements for Dusty Dvoracek and Clint Ingram.

And the secondary has been shuffled.

There's plenty for football fans to obsess about in the next 15 practices.

Never mind that many _ most _ of these questions won't be settled until August.

There's plenty of time.

But in a strange way, development at the positions where the questions have been answered might be the Sooners' most important task of the spring.

"Our challenge," Wilson said, "is to get our young guys to bind and to continue developing."