Of that group, there are far more failures than successes. Roethlisberger and Trent Dilfer are the only ones to have won Super Bowls as starters. Three junior quarterbacks chosen with the first overall pick — Jeff George (1990 Indianapolis), Tim Couch (1999 Cleveland) and Alex Smith (2005 San Francisco) — never made the playoffs with the team that drafted them.

For every Drew Bledsoe, there are washouts like Ryan Leaf, Andre Ware, David Klingler and Heath Shuler. All four were top-seven picks prematurely shoved into starting spots without strong surrounding casts, or in the case of college run-and-shoot quarterbacks like Klingler and Ware, any degree of comfort running pro-style offenses. Leaf, Ware, Klingler and Shuler never recovered from rough NFL initiations and were gone from the team that drafted them within four seasons.

As for the rest of the big-name underclassmen, the jury remains out on three recent first-round choices: Green Bay's Aaron Rodgers, Tennessee's Vince Young and Oakland's JaMarcus Russell. And then there are those whose careers were derailed by off-field problems: Michael Vick, Quincy Carter and Todd Marinovich. Vick is in prison for running a dog-fighting ring. Carter and Marinovich have both battled hardcore drug addiction.

It's fair to wonder whether their fate would be different had all three had an extra year to mature in college.

"Some (junior quarterbacks) are not ready physically," Colbert said. "Most are not ready emotionally."

That's not to say teams with quarterback needs are complaining about this year's junior entries.

There might not have been a first-round selection at the position had Stafford and Sanchez returned for their senior seasons. Freeman and Davis are likely to get chosen between the second and fourth rounds.

Grading these players presents a challenge for scouts and personnel directors because of a more limited body of work than most NFL-caliber senior quarterbacks. Interested teams will pay especially close attention during workouts and interviews this weekend at the NFL Scouting Combine in Indianapolis.

"During the fall, you're not scouting the juniors because you don't know if anyone intends to come out or not," Colbert said. "You'd be wasting your time if you try to track down every rumor and would not be able to concentrate on the guys that are eligible for the draft."

Of the four junior quarterbacks, Sanchez will face the heaviest scrutiny because he made only 16 college starts.

"Historically, quarterbacks who don't start over 30 games never really perform up to what you thought," said NFL draft expert Gil Brandt, who was the Dallas Cowboys' top talent scout from 1960 to 1989. "Sanchez started 16 games. You can look at 15 starts and he doesn't look very good. The 16th versus Penn State (in the 2009 Rose Bowl), he looks like the best quarterback of all time. Which Sanchez are you getting is what it amounts to."

It will cost a potential suitor like Detroit or Kansas City dearly to find out if Sanchez is chosen with one of the draft's first three picks. The Lions, which pick first overall, and Chiefs (third) would be expected to pay more than the six-year, $72 million contract that Matt Ryan received from Atlanta as the No. 3 choice in last year's draft.

Ultimately, both squads may find it cost prohibitive to pick a quarterback so early in the draft. But if Sanchez or Stafford blossoms like Roethlisberger, it will be money well spent.

Alex Marvez interviewed Gil Brandt while hosting on Sirius NFL Radio.