There’s one thing Gary Patterson must check off his list at the start of a typical game week in order to prevent any sleepless nights.

Known as a defensive guru, TCU’s longtime football coach determines how to play against the run and pass of his opposition. That’s just the first night. Then he’ll look at specific personnel groups and what they run out of certain packages.

“First thing I gotta decide is how I'm going to play leverage on these guys and what things they do really well that I've gotta slow down,” Patterson said recently at Big 12 Media Days.

“I gotta know that before I go to bed.”

For the first six years in the Big 12, that preparation has proved successful with TCU holding a claim as the only team in the league since 2013 to boast a Top 25 scoring defense.

What Patterson has figured out, or honed in on, since joining the league from the Mountain West sees the remaining Big 12 defenses still trying to attain. Plagued by perception issues as an offense-only conference, Big 12 coaches and players weighed-in on what the ideal recipe is for a successful defense.

“You're not going to stop these passing games in the Big 12 with great (defensive back) play,” Baylor coach Matt Rhule said. “You're going to stop it with a pass rush.”

TCU, the Big 12’s top defense in 2017, led the league with 42 sacks. Texas and Iowa State, the league’s second- and third-ranked defenses, finished second and tied for third, respectively, in that category.

Tackling in the open field helps. Pressure to stop the run is key, too. TCU, Texas and Iowa State ranked first, second and fourth in stopping the run.

“The thing I've seen is you have to have really good players, you gotta be really good up front, you gotta have quality depth,” said Oklahoma coach Lincoln Riley. “That's maybe some of the areas we've lacked the most, especially the depth. We have to get back to being dominant up front. We've had our flashes. We've had our moments.”

In a climate where the Big 12 is continually marketing itself as a viable College Football Playoff contender, a decade worth of numbers show defense matters. Eight of the last 10 college football title winners ranked inside the Top 10 of total defense and scoring defense.

The one true outlier is Auburn, which overcame defensive ranks of 60th and 53rd to win the 2010 title thanks to Heisman Trophy-winning quarterback Cam Newton. Oklahoma nearly put this theory to rest last year, showing how an elite quarterback like Baker Mayfield can neutralize a subpar defense (67th in total defense; 68th in scoring defense) and make the CFP semifinals.

Moreover, seven of the last 10 runner-up challengers ranked among the Top 12 in either category. The 16 semifinalists since the CFP’s inception, on average, ranked 23rd in total defense and 24th in scoring defense.

Those numbers encompass five different conferences. Most players said playing defense in the Big 12 is a different animal. Speed and conditioning are needed.

“It's an up-tempo, upbeat league,” said West Virginia linebacker David Long. “To be good, you have to be relentless, in shape and just focused.”

The fine details matter. Baylor defensive end Greg Roberts said taking a steady approach is the base of it.

“You can't come and have an off day — well, you can. You'll get burnt,” he said.

From a schematic standpoint, Iowa State coach Matt Campbell, who helped orchestrate a massive defensive turnaround, said the key is multiplicity as to not show the same thing over and over again.

Campbell posed two questions this offseason: How can the Cyclones improve? And what do they need to evolve/change knowing they no longer will catch teams off guard?

“No matter what style of football you want to play, does your offense match your defense to allow you to have the best success possible?” he said. “I know that's something that's really important from our end of it.”

In general, Patterson said two years is needed for a defense to adjust.

Campbell is entering his third year at Iowa State. Rhule and Texas coach Tom Herman are in Year 2 of their systems, and Rhule expects his players to start flying around more due to an increased comfort level.

“When they first got here, it was like they were speaking Chinese to us,” Roberts said. “It was like a foreign subject. We didn't understand the concepts. We couldn't comprehend it. Now we can speak football with them.”