"Sometimes, players get trapped into roles they're not ready for and don't have the success you're hoping for. Sometimes, they can be judged too quickly."

The NFL landscape is littered with examples of both.

Thirty-nine junior and redshirt-sophomore quarterbacks have entered the draft since 1989. That was the first year the NFL granted admission to underclassmen three seasons removed from high school.

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.