NORMAN, Okla. — If a cornerback defends 80 plays in man-to-man coverage, that could easily be the equivalent of 80 60-yard sprints. If that sounds exhausting, it's because it is — even for a 20-year-old in top physical condition.

Receivers go through the same excursion. The difference is they don't have to tackle anyone, and they know where they're going. They also benefit from sharing time with at least one other receiver at that spot. They run a 60-yard go-pattern and then slide off to the sideline after the play. A fresh receiver steps in. That cornerback or safety that sprinted stride for stride tries to catch his breath in the 20 seconds before the next play.

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OU defensive backs coach Kerry Cooks would love to be able to pull a cornerback like Jordan Thomas after that mad dash. Cooks believes the Sooners are at the point where he can.

"The base philosophy is there is a thing, in my mind, to where we have a key starter, which is a guy who can play championship-level football for 50-70 plays. And then there's a starter. Key starters are guys that you put a lot of pressure on and you rely on," Cooks said. "And then the starters are guys who can come in and play winning football for you. They just may not be ready to [get to] that next level and be a key starter, but if they can come in and take 15-20 reps off of you, that's helping the team."

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The Sooners have three established defensive backs heading into the season. Safeties Steven Parker and Ahmad Thomas have played in virtually every game since the start of the 2014 season. Cornerback Jordan Thomas mirrors that experience. The real competition battle is at the other cornerback spot with Dakota Austin and Michiah Quick fighting for the spot.

But what happens if sophomore safeties Will Sunderland and Kahlil Haughton can spell them for 20 plays a game? What if sophomore P.J. Mbanasor or true freshmen Parrish Cobb or Parnell Motley can fill in after covering that go route.

"You want to be able to rotate, but you need to have confidence they can get the job done, too," defensive coordinator Mike Stoops said.

Finding a big supply of trustable defensive backs is always a preseason goal. There are 85 scholarship players. The coaching staff would live to figure a way for all to contribute on Saturdays. The last two-and-a-half weeks have not been any different than the past dozen years.

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Cooks' concept has merit. OU's done this with its defensive line for years. It's rare for a lineman to play more than five or six plays in a row without a breather.

Cooks had the same philosophy with the secondary when he was the defensive backs coach at Notre Dame. He desperately wanted to implement it at OU when he knew up-tempo offenses -- Baylor, Oklahoma State, TCU and Texas Tech -- were annual adversaries.

"Guys can't play 100 percent at 100 plays. I don't care how talented they are. You're going to get tired; you need a break," Cooks said. "Even if it's a mistake, I want to have that confidence to send a No. 2 in. Come off with the ones, correct the problem and send him back in. It's about buying into the concept of playing fresh and being fresh the whole game."

This also keeps more of the secondary engaged. The Sooners like what they've done recruiting wise the in the last two classes. Getting younger players on the field helps develop them for when they take over those No. 1 spots.

"I feel like this year, everyone is really getting it," Parker said. "To me, that's the difference between last year and things year. I feel like we could be one of the best secondaries."

This article was written by John Shinn from The Norman Transcript, Okla. and was legally licensed through the NewsCred publisher network.