INDIANAPOLIS — The roots of how Texans quarterback Deshaun Watson creates confusion for defenses were born through triple-option concepts that first became popular in high school and college football.

Run-pass option plays have become trendy in the NFL behind masters of the craft like Watson and other dual-threat quarterbacks capable of dominating defenses with their arms, feet and minds.

When Watson momentarily stuck the football in the belly of running back Carlos Hyde as tight end Darren Fells cut across the line of scrimmage and pretended to throw a block, the well-executed, run-pass option play paralyzed the Kansas City defense a week ago at Arrowhead Stadium.

Believing it was a run, the Chiefs reacted aggressively to Hyde heading up the middle without the ball. That left Watson with no one to stop him from making a fast read as a wide-open Fells looped into a short pass pattern and caught the ball in stride during a 31-24 victory that included several crisp run-pass option plays.

The run-pass option has emerged as a dangerous weapon for Watson and a Texans offense that’s starting to hum heading into Sunday’s game at Indianapolis. And the strategy is as tailor-made as a bespoke suit for Watson, who has been operating this way since his days as a blue-chip recruit from Georgia who won a national championship at Clemson.

Hamstring injury sidelines CB Roby INDIANAPOLIS — The Texans downgraded starting cornerback Bradley Roby from questionable to out for Sunday’s game at Indianapolis because of a Grade 2 strained hamstring. Roby, who did not travel with the team, was not expected to play Sunday because of the severity of a leg injury suffered last week against Kansas City. The Texans will start Johnathan Joseph, who returns from a less serious strained hamstring that kept him out against Kansas City, opposite rookie corner Lonnie Johnson Jr., and Phillip Gaines as the nickel back. Aaron Wilson

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The run-pass option, or RPO, involves Watson appearing to hand the ball off in a manner similar to a classic play-action fake.

Watson reads a specific defender on the fly or before the snap at the line of scrimmage. Sometimes, it’s a defensive back Watson uses as his key. Sometimes, it’s a designated front-seven defender. As the play unfolds as the offensive line run blocks, Watson taps into his knowledge of defenses developed through years of film study and his natural instincts to make a choice.

It’s a called run play with a pass option for Watson to decide on.

Watson can simply hand the ball off, which is a sound option with the power and burst of Hyde at his disposal.

Watson can keep it himself, another good way to operate considering he’s already rushed for five touchdowns in six games.

Or Watson can deliver a throw to an inviting target like Fells because of the respect that defenses pay Watson as a running threat along with a strong running game led by Hyde. The Texans are averaging 5.0 yards per carry and 139.8 yards per game to rank fifth in the league in rushing offense. They’re eighth in scoring with a 27.0 average per contest.

The run-pass option effect with Watson at the controls is puzzling to opposing defenses.

“It definitely causes some confusion for the defense,” Hyde said. “They don’t really know what we’re doing. We have so many different options. We can run and pass all in one play. It breeds confusion. It’s been working for our offense. It’s definitely we’ve been building on and we need to keep that going.”

The success of the run-pass option has defenses searching for ways to counteract one of the most challenging offensive plays and quarterbacks in the game.

The Texans’ pass protection is significantly upgraded behind new left offensive tackle Laremy Tunsil. With Watson making faster decisions and showing improved pocket awareness, the line has allowed no sacks in consecutive games for just the second time in franchise history.

And the ability of Watson to make the correct read on a preselected defender prior to the snap and carry out fakes is keeping defenses off-guard and hesitant.

“It’s just another dimension to our offense,” wide receiver Keke Coutee said. “There’s a lot of different things we can do and different ways to get the ball in different guys’ hands. That’s been a big part of our offense.”

Run frequently by the Chiefs with reigning NFL MVP Patrick Mahomes, Philadelphia with Carson Wentz, Baltimore with Lamar Jackson and several others, the run-pass option is all about fooling the defense.

If the defense makes the wrong choice, then the quarterback is left with easy plays for the taking as he piles up yards with his feet or his arm.

“Anytime we put the ball in Deshaun’s hands, good things are more likely to happen,” Texans offensive coordinator Tim Kelly said. “So, really we’re just trying to take advantage of his natural skillset and really design plays that are going to help us gain yards.”

Watson entered the NFL adept at freezing defenses with play-action fakes. He’s only gotten better at it now in his third season.

Watson has completed 69.7 percent of his throws this year for 1,644 yards, 12 touchdowns and three interceptions for a 107.9 passer rating.

Between the presence of Hyde, who has rushed for 426 yards and three touchdowns and Duke Johnson, the Texans have another wrinkle that defenses have to respect. That provides a boost to the run-pass option plays Watson excels at and enjoys running.

“I think any time you run the football, I think that usually has a pretty good effect on how well your play-action game takes effect,” Kelly said. “That’s not always the case. I think a lot of that has to do with ball handling and the action and all of those different things, but I think that running the ball definitely helps.”

None of this works without the elements of blocking and a physical running game that defenses have to account for.

Against the Chiefs, Hyde busted into the end zone untouched for one of the Texans’ four red-zone touchdowns out of six opportunities.

Former Texans safety Tyrann Mathieu, who signed with Kansas City in March, made the choice not to engage in a collision with the 6-foot, 230-pound Hyde.

“That was an easy walk-in for Carlos,” Coutee said. “Business decision, they didn’t want no part of that.”

Because of how Watson operates the offense, his mental acumen and how coach Bill O’Brien and Kelly are designing game plans, the Texans are in a ton of advantageous situations.

The offense demands a lot out of the quarterback, but Watson, 24, is well-equipped to beat defenses as a student of the game.

“I knew it when I was coming in,” Watson said. “That was one of the biggest things, especially playing in this offense and playing for coach O’Brien, you’ve got to be smart and know what the defense is doing. That’s the only way you can really be successful in this league is knowing where to go with the ball and understanding what defenses are wanting to do.

“But as far as learning, I’m always learning, always finding new ways to try to attack different defenses and then defensive coordinators are also trying to do different things. As a course of a career, I continue to grow. I continue to learn and study as much as I can.”

aaron.wilson@chron.com

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