UCLA’s offensive coordinator is keeping a close watch on Josh Rosen

There will come a cut-the-cord moment for UCLA quarterback Josh Rosen and offensive coordinator Noel Mazzone. For now, Mazzone stays close enough that he buzzes in Rosen’s ear during practice.

Rosen, the first UCLA freshman quarterback to start a season opener, will make his third start against Brigham Young on Saturday at the Rose Bowl. He looked ready to fly solo in the opener against Virginia, throwing for 351 yards and three touchdowns. The follow-up against Nevada Las Vegas — when he passed for 223 yards and one touchdown, with one interception — showed he still needed a flying instructor.

Mazzone positions himself behind the offense when it works against the scout team during practice. He is there to answer questions and correct mistakes.

“I never like being on the field during scout team periods because I’m not on the field during the games,” Mazzone said. “It’s not like he needs me out there. You know what, maybe it’s more for my reassurance than his, ‘Oh, he’s seeing this right and he’s seeing that right.’”

Whoever gets the most out of being tethered, it will go on for a while.

Rosen has appeared confident and poised while getting his feet wet and uniform dirty at the college level. He had spring practice and training camp to cultivate knowledge of the offense.

But he is still just a freshman.

Former UCLA quarterback Brett Hundley went through a similar maturation process in 2012, when he was given the keys to Mazzone’s offense as a redshirt freshman.

“I knew after two years what Brett was thinking, I was thinking most of the time,” Mazzone said.

Mazzone backed away around the middle of Hundley’s second season.

“That first year he was like, ‘Let’s call plays and go and whatever happens happens,’” Mazzone said. “The second year, he really started to understand how all the pieces fit together in the offense.”

So for now, Mazzone will look over Rosen’s shoulder. “I just want to make sure he’s seeing stuff the same way I see it,” Mazzone said.

Tall order

BYU’s receiving corps includes two difficult assignments for defensive backs: Mitch Mathews is 6 feet 6, Nick Kurtz is 6-5.

UCLA cornerbacks Fabian Moreau and Marcus Rios are 6-0 and 5-11.

“If you can get your hands on them early, it helps you,” UCLA Coach Jim Mora said of the matchup. “We get to play against some pretty good-size guys around here.”

Good-sized, but not that tall. UCLA receivers Thomas Duarte, Eldridge Massington and Austin Roberts are 6-2; Alex Van Dyke is 6-4.

“You can’t grow,” Mora said. “We don’t have any magic beans to give them. We just try to disrupt [receivers], time it to make the play when the ball arrives.”

UCLA has grown up a little at cornerback. Last season, 5-8 Ishmael Adams started ahead of Rios.

“I’m feeling a lot more comfortable out there,” Rios said. “But I can’t stop working. I have guys pushing me from behind.”

Adarius Pickett, who is 5-11, has taken the nickel back spot that was slotted for Adams, who was arrested Aug. 30 on suspicion of taking a cellphone from an Uber driver.

(Bad) Memory lane

UCLA has a 7-3 record against BYU, but has lost the last two games. Both were painful, defensive line coach Angus McClure can attest.

The Bruins lost to the Cougars, 17-16, in the 2007 Las Vegas Bowl when kicker Kai Forbath had his low kick on a short field-goal attempt blocked.

“Blocked by a young man who didn’t even jump,” said McClure, the Bruins’ tight ends coach that season. “It was cold and Kai wanted to keep the kick low because of the distance.”

McClure remembered that as the last time UCLA played BYU. But the next season the Bruins were scorched in Provo, Utah, 59-0.

McClure was the program’s on-campus recruiting coordinator that season. “Oh, that’s right,” he said, “I guess I have erased that game from my mind.”

chris.foster@latimes.com

Twitter: @cfosterlatimes