Big defensive plays were key to Kansas State winning the Big 12 and the BCS bowl that goes with it. (US Presswire)

The Big 12 is a league known mostly for its wide-open offenses. But it is quality defense that ultimately helped determine the conference championship.

It isn't easy being a Big 12 defensive coordinator. There must be plenty of gray hairs growing and sleepless nights worrying about what comes next. After all, four of the nation's top-10 scoring offenses and six of the top 16 are members of the Big 12.

Thus it's little surprise that only one Big 12 team is in the top 30 in scoring defense. But that was the key to Kansas State's ability to win the league title and an automatic BCS bowl berth. The Wildcats are on our list of top-five defensive performances twice, but three individual efforts stand out as well.

1. Kansas State forces key turnovers to win at Oklahoma on Sept. 22

The game that ultimately decided the Big 12 champion was between the Wildcats and Sooners in Norman. Kansas State won, 24-19, but did so almost entirely thanks to its defense. Jarell Childs picked up a Landry Jones fumble and returned it for K-State's first touchdown. A later fumble by OU's Blake Bell came at the Wildcats' 1-yard line and ended a scoring threat. Kansas State's Ty Zimmerman added a pick of Jones late in the third quarter to set up another short touchdown drive. Those plays made the difference in the game -- and the Big 12 season.

2. Iowa State LB Jake Knott makes critical play in win over Baylor on Oct. 27

Knott's season came to an early conclusion due to a shoulder injury. Before that, though, he was playing as well as anyone in the Big 12. He made multiple big plays early in the season (including a game-sealing interception late in a win at rival Iowa) but was at his all-around best against the Bears in a 35-21 win. Knott had 11 tackles and forced a fumble at the goal line to end a Baylor scoring threat while leading an Iowa State defense that had two key fourth-down stops. It was only the second time in 30 games Baylor was held to fewer than 30 points.

3. TCU's Kenny Cain keeps Virginia from thinking upset on Sept. 22

The Horned Frogs had their ups and downs in their first Big 12 season, but Cain helped ensure they didn't take an upset loss early in the year. The linebacker had two interceptions and a fumble recovery, ending multiple UVA drives that seemed likely to end in points, helping TCU win 27-7. The Horned Frogs' offense failed to put the game away early, and Cain's turnovers were key because both picks came on the TCU side of the field.

4. DB Allen Chapman's three picks keep Kansas State unbeaten on Nov. 3

One way to shut down an explosive offense? Force turnovers early and often. That's what the Wildcats did against Oklahoma State, picking off four passes and forcing five total turnovers in K-State's 44-30 win. Chapman led the effort for the Wildcats, picking off three passes -- the most by a Kansas State player since 1995. Chapman returned the first one for a critical touchdown. For his efforts, he was named Walter Camp national defensive player of the week as the Wildcats remained unbeaten.

5. Texas' Alex Okafor does it all vs. West Virginia on Oct. 6

It's rare to see the Big 12 honor a player in a losing effort. But Okafor, the Longhorns' star DE, merited the recognition after a strong all-around performance in a 48-45 loss to the Mountaineers. Okafor had two sacks (WVU had allowed only four in the first four games of the season), two forced fumbles, a blocked field goal and three quarterback hurries. He was the only thing that kept West Virginia's offense from having even more of a field day.

For more up-to-the-minute news and analysis from Big 12 bloggers C.J. Moore and Patrick Southern, follow @CBSSportsBig12 on Twitter. You can also follow C.J. (@cjmoore4) and Patrick (@patricksouthern).