Bill Snyder's unit has lots of raw talent and brings back seven starters from a defense that ranked fifth in the Big 12 last season. Linebacker Arthur Brown holds it all together in the middle, but cornerback Nigel Malone could emerge as the Big 12's best by season's end. Fellow defensive back Ty Zimmerman and linebacker Tre Walker are both very underrated.
TCU had a rough 2011 season, and lost former All-American Tanner Brock before the season when he was arrested in a campus drug sting. The Horned Frogs have a tried and true defensive system, though, and safeties coach Chad Glasgow returns after a season at Texas Tech. Under coach Gary Patterson, the Horned Frogs led the nation in total defense in 2008, 2009 and 2010.
The Cowboys came under fire last year under the national microscope, but OSU still forced 44 turnovers in 13 games, six more than any team in all of college football. Eight starters return, including an outstanding cornerback duo in Justin Gilbert and Brodrick Brown. Linebacker Shaun Lewis could be due for a breakout season, too. There are some questions on the defensive line, but Alex Elkins and Caleb Lavey fill out a strong set of linebackers.
The Sooners' back line caught a lot of criticism last season, but Mike Stoops is back, 11 years after helping carry Oklahoma to its seventh national title, pitching a shutout of Florida State in the 2001 Orange Bowl. He'll help revitalize the secondary in Norman, and has plenty of talent at his disposal to do so, highlighted by Tony Jefferson, who looks like he's found a home at the traditional safety spot after spending two seasons as nickelback. Corey Nelson and Tom Wort give the Sooners one of the best sets of linebackers in the league.