OXNARD, Calif. -- Time after time during individual drills Sunday, Dak Prescott kept throwing deep.

A straight go route. A stop-and-go. A slant-and-go. An out-and-up. Any variation of the deep ball, Prescott kept firing it to his wide receivers. First it was Terrance Williams. Then Tavon Austin. Then Lance Lenoir. Williams again. Austin again.

Most of the time the passes were in good spots, leading the receivers into a position to make a play, but not the defensive backs.

Dak Prescott throws deep for Michael Gallup against the 49ers last Thursday. Throwing long passes is not an afterthought for the Cowboys, as every team must have that threat in order to keep defenses honest. John G. Maganglo/WPA-EFE/REX/Shutterstock

Prescott's best delivery came on an out-and-up to Lenoir, who turned cornerback Anthony Brown around, but Lenoir couldn’t hang on to the pass as it came down from the sky.

“We’ve got some guys that can really stretch the field,” Prescott said. “We knew that coming into the offseason and then going into training camp that was part of our game we needed to strengthen and we needed to get better. And with having some guys that can stretch the field, it’s important that we all get on the same key there.”

The go route will not be a staple of the Dallas Cowboys' offense in 2018, but Prescott knows it has to be a part of it if the unit wants to be successful.

Everybody knows the Cowboys will want to give the ball to Ezekiel Elliott often. They will make their living on how well they run the ball. In Elliott’s first two seasons, the Cowboys have run the ball extremely well. He led the NFL in rushing as a rookie and averaged 98 yards per game in the 10 contests he played in 2017.

“Sometimes you’ve got to throw it and make the defense back up,” Prescott said. “It’s not a live-or-die thing, but we’ve got to take advantage of the opportunities when they give it to us because if not, they’re just going to sit on underneath routes. So we’ve got to let them know we can beat them over the top and let them know otherwise.”

Early in training camp, Prescott and the receivers struggled on deep balls. Passes were either too long or a little too short. The receivers did not do a good job of giving Prescott an avenue to get the ball to the outside, sticking too close to the sidelines.

But on the first drive of the first preseason game against the San Francisco 49ers, Prescott connected with rookie receiver Michael Gallup on a 30-yard touchdown.

To Cowboys coach Jason Garrett, a good deep-ball thrower must see the defense quickly and understand the route concept first. Then the quarterback must have his feet in good position to put the proper touch and accuracy on the throw.

“I think there’s a misnomer that good deep-ball throwers have to be guys with the strongest arms, that they throw it the farthest down the field,” Garrett said. “If you go back 100 years in football, '9' routes, straight go routes, are completed 42 yards down the field. That’s typically where they’re completed.”

Last season, Prescott ranked eighth in QBR (91.4) on passes that traveled 20 or more yards in the air, according to ESPN Stats & Information research. He completed 34.9 percent of those passes, which was 12th-best. Three of his 15 completions of throws 20 or more yards went for touchdowns, with all three coming in the fourth quarter.

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In his first two seasons, he is sixth in QBR in passes of 20-plus air yards (96.1) and he has nine touchdown passes.

For years, Dez Bryant was the Cowboys’ big-play threat outside, although Williams averaged 15.8 yards per catch in the first four seasons of his career. At 5-foot-8, Austin and Cole Beasley don’t have the prototypical size of the outside receivers, but Prescott has not been shy in taking shots to both. Allen Hurns made plays down the field during his time with the Jacksonville Jaguars, but he is more likely to make contested catches in traffic. Deonte Thompson might be the Cowboys’ fastest receiver, but he has been slowed by an Achilles injury in camp. Gallup, the third-round pick, has showed an ability to make plays in camp.

“Dak’s got to get that extra work with those guys,” offensive coordinator Scott Linehan said. “Just the whole idea of the deep ball, we want to stretch it and get it down the field. That’s really where the whole 9-ball concept works, when you’re really looking to get that ball. Not always the bull's-eye shot or the back-shoulder throw. To me, those are changeups or things you do when people defend it.

“Right now the real premium is on closing that cushion, getting on top and throw that ball to a spot.”

And that’s why Prescott kept throwing deep Sunday.

“The best deep-ball throwers I’ve been around, you spend time on it,” Garrett said. “Sometimes it feels like it’s an afterthought that we’re going to throw a go route, that it’s like the last route that we work on. But the best ones I’ve been around, they work on it a lot. There’s a real art to running those routes and a real art to throwing them.”