AUSTIN, Texas -- Texas has a well-earned reputation as the nation's "DBU," a proverbial factory of NFL defensive backs.

Even so, when three NFL-caliber corners leave a team, like they did at Texas before the 2011 season, doubts will surface.

Can you replace Aaron Williams' versatility? What about Curtis Brown's cover skills and Chykie Brown's knack for being in the right place for the big play at the right time?

New defensive coordinator Manny Diaz looked down his depth chart and saw a true freshman, Quandre Diggs, and a little-used sophomore in Carrington Byndom.

By season's end, though, the duo transformed one of the Longhorns' biggest question marks -- and after a 5-7 season in 2010, they had plenty -- into arguably its biggest strength.

"Both of them are both very bright," coach Mack Brown said. "They made an easy transition to the field. Both of them were in very good high school programs."

Diggs showcased his fearlessness early in the spring. He went head-to-head with -- and held his own against -- the team's top and more experienced receivers while he should have been in high school. The contact did not faze the former high school running back.

"Quandre was tough," Brown said. "He got knocked around a lot."

Meanwhile, Brown pointed to Byndom's outstanding athletic ability for his early success. Byndom had the option to play college baseball, but elected to stick to football.

"Carrington has gotten tougher every minute he's been here," Brown said, adding that he was a "very good athlete."

By fall, both were entrenched as starters.

Diggs finished the season with four interceptions, more than all but one freshman in college football (Bryce Callahan of Rice). The league's coaches named him the Big 12's top defensive freshman and Diggs was named a freshman All-American. He landed a spot on the All-Big 12 second team, too.

Byndom, a first-year starter, landed a nod as a first-team All-Big 12 talent and a key cog in a defense that topped the conference in total defense for a fifth consecutive season. He picked off two passes and tied Diggs with a team-high 15, earning the team's defensive player of the week honors on four occasions.

Notes KC Joyner of Football Outsiders:

His 6.2 yards per attempt (YPA) allowed total was better than the YPA marks posted by Alabama Crimson Tide cornerback Dre Kirkpatrick (6.6) and LSU Tigers cornerback Morris Claiborne (7.5), two coverage specialists who will likely end up selected in the first round of the 2012 NFL draft.

DBU, indeed.

The Longhorns also were the only team in college football to not allow a touchdown pass for 20 yards or longer before the season finale against Heisman winner Robert Griffin III and receiving champ Kendall Wright.

"They were very responsible," Brown said. "That was one of our biggest question marks sitting there in the spring and in the fall. And I thought you have to give a lot of credit to Manny and to [defensive backs coach] Duane [Akina] for devising a scheme that took pressure off of them as well.

"We didn't play near as much man and didn't put them in as many one-on-one situations, and then because of their confidence you see the play that Carrington made at A&M probably changed that game."

Byndom swung the momentum for the burnt orange in the final chapter of a heated rivalry with the in-state Aggies before they left for the SEC.

Trailing 16-7 at halftime, Byndom stepped in front of a Ryan Tannehill pass early in the third quarter, returning it 58 yards for a touchdown, silencing a rabid Kyle Field crowd and igniting a second-half comeback for the ages.

Brown saw plenty out of both corners in 2011, but they were young and inexperienced. What happens now?

Big 12 receivers, beware.