Part of the Doc's Big 12 Week.

The focus behind Oklahoma's unanimous top-five projections has been overwhelmingly on Sam Bradford's return, for obvious reasons: You know, Heisman-winning quarterbacks who lead the nation in pass efficiency two years in a row and orchestrate the highest-scoring season in college football history don't grow on trees. Throw in two 1,000-yard rushers and the best receiving tight end in the country and that's an automatic championship contender.

Of course, they're all forced to recognize the four new starters on the offensive line, too although usually as a kind of afterthought: Oh yeah, they have to replace those guys -- maybe we'll rank OU No. 3 instead of No. 2. The defense is the issue. But those guys, multiyear starters who were together for nearly every significant snap of Bradford's first two seasons and allowed fewer sacks than any other team in the Big 12, don't seem like the type you expect to immediately replace:

OU Departed Offensive Linemen
 • Phil Loadholt: 27 career starts; All-Big 12 (2007-08); Drafted 2nd Round
 • Duke Robinson: 40 career starts; All-Big 12 (2007-08); All-America (2007-08); Drafted 5th Round
 • Jon Cooper: 43 career starts; All-Big 12 (2008); Big 12 Lineman of the Year (2008)
 • Brandon Walker: 41 career starts

For fellow liberal arts majors, that is 151 career starts exiting the premises, not including another 17 by veteran Branndon Braxton, along with a pair of draft picks -- neither of whom was selected by coaches as the best lineman in the conference. If Bradford had turned pro early, the Sooners would certainly be entering a "rebuilding" year at the fringe of the top-10/12 and given no chance to challenge Texas in the Big 12, no matter who was coming up behind him. But isn't 80 percent of the offensive line as integral to the offense as its extremely well-protected quarterback, if not more so? Or the running backs who rack up staggering numbers running behind them? Not that last year's ungodly sums seem replicable under almost any circumstances, but wholesale turnover up front should guarantee a substantial drop.

The more relevant question is how far the numbers will fall, and whether the dent will be too deep to beat Texas and/or avoid the random upset that could snuff out the push for both the Big 12 and the mythical championships. As steadily brilliant as Bradford's been, his success is still intricately wrapped up with the line, which made him the best protected 20-year-old in America. It's even a little chicken-and-egg: To what extent did the outstanding protection make Bradford and the rest of the offense? Is he the same quarterback without them? These are fair questions, given that Bradford has taken so few hits, and that the teams that have had the most success against OU have invariably been the ones that hit him the most: Of the dozen sacks on Bradford last year, ten of them were by TCU (fours sacks), Texas (three) and Florida (two), unquestionably the Sooners' worst games of the year -- the Frogs and Longhorns each held OU to 35 points, the only teams to keep them below 45, and of course the Gators managed to hold Bradford and Co. to a stunning 14 points in the championship game, in which the biggest play may have been a red zone interception Bradford lobbed under pressure right before the half, with the Sooners driving to take the lead. Texas and Florida featured by far the best edge rushers (from both ends of the line) on OU's schedule, and it's no coincidence that Bradford was intercepted twice by both teams in OU's only losses. Going back to the Sooners' defeats in 2007, Colorado also forced Bradford into a pair of picks; Texas Tech knocked him out of the game in the first half; and West Virginia sacked him three times in the bowl game.

The only holdover from last year is right tackle Trent Williams, an All-Big 12 pick by league coaches and an All-America by a lot of the preseason magazines, who's moving to the left side. The other four projected starters are what you'd expect from Oklahoma: All came in as top-10 prospects at their respective positions and members of the Rivals250 list of the best incoming prospects overall. One, new right guard Stephen Good, was a five-star billed with a penchant for nastiness. Another, senior Brian Simmons, was an elite prep school prospect who's played in every game the last two years. In those terms, even with the surprise transfer of a former top center prospect, Jason Hannan, this line is more talented/hyped than the one that precedes it.

But when Bob Stoops publicly called out the entire line for poor winter conditioning before spring practice, the urgency came into focus: If this group can't at least approximate the fortress of solitude the last starting five typically erected around the pocket, Sam Bradford's star -- along with the Sooners' highest ambitions -- will come crashing to Earth sooner or later.