Then-defensive back Preston Rex was walking to the parking lot west of the Student Athletic Building last summer after a morning workout when he came across BYU football coach Kalani Sitake.
“I’ve been meaning to talk to you about something,” Sitake said, calling Rex over to his truck. “What would you think about switching to running back?”
Rex was stunned.
“Here fall camp is about to start, and coach is talking about me making a major position change,” Rex said during BYU’s photo day on Wednesday. “I am like, ‘Hey coach, what are we doing here? Are you serious?’ But he was serious, and here I am.”
Rex, the brother of former BYU tight end Isaac Rex and son of All-American BYU tight end Byron Rex, was a star safety and receiver out of San Clemente High in California before signing with BYU in 2020, but had never really played running back before.
“I’m super happy I did it. No regrets at all. I mean, Rexes are offensive guys, right? We like the ball in our hands. We like to block. We like to score touchdowns.”
— BYU running back Preston Rex
He immediately called his brother and dad to get their take on the situation, then called BYU offensive coordinator Aaron Roderick, who was on the same page as Sitake. Preston Rex called Sitake a few days later and told him he was on board to move over to the offensive side of the ball.
The rest is history. Although the 6-foot-1, 200-pound senior with two years of eligibility remaining hasn’t supplanted superstar LJ Martin as RB1 on the depth chart, he’s been a quick study in the running backs room, Roderick said on Monday.
“I’m super happy I did it. No regrets at all,” Rex said Wednesday. “I mean, Rexes are offensive guys, right? We like the ball in our hands. We like to block. We like to score touchdowns. So no regrets at all.”
When Rex was flagged down by Sitake in the parking lot some 13 months ago, he was still trying to get back into playing shape, having sustained an ACL injury in practice after the 2024 season opener against Southern Illinois. That injury caused him to miss his third year in the program. He had redshirted in 2022 after a church mission to Chile and McAllen, Texas, and appeared in nine games in 2023, making 17 tackles.
Ever positive, like his brother, Rex said the injury paved the way for BYU to develop other safeties such as Faletau Satuala and Raider Damuni and give them early playing time.
“The amazing medical staff really took good care of me, and they made my knee even better and stronger than it was before,” he said. “It’s all good.”
But playing running back, and all the wear and tear that comes with it, would still require a big leap of faith.
“I feel like Heavenly Father was opening a lot of doors for me, for the switch,” he said. “And so it was something that I committed to. I said, ‘I will do whatever is best for the team. I am a team guy.’ It was a pretty late switch, coming right before fall camp, but it was in the best interest of the team.”
Days after fall camp opened last summer, it became apparent why Rex was asked to make the switch. Redshirt freshman Pokaiaua Haunga, an RB who showed flashes of brilliance in 2024, was dismissed from the program.
Playing behind Martin and battling Jovesa Damuni, Sione Moa and Enoch Nawahine for playing time and touches, Rex appeared in 12 games in his new position and had 13 carries for 30 yards, with a long of nine.
He proved to be a capable pass-catcher out of the backfield, with three receptions for 50 yards. His 32-yard reception helped BYU beat Utah 24-21 last October.
“That was sweet,” he said.
Toward the end of the season, Rex dealt with a torn AC joint in his shoulder that limited what he could do. Which brings us to 2026. The veteran is fully healthy and ready to fill in where he’s needed. He said there is a “night and day difference” between last year and this year.
“I am really excited about the improvement that Preston Rex has made since last year. He got thrown into a tough situation. He wasn’t really a running back, and he had to learn to play it on the fly, and he did make some good plays for us last year in the open field.”
— BYU OC Aaron Roderick on running back Preston Rex
“I feel 100% more prepared,” he said. “Having a full offseason to really just learn the ins and outs of the offense, and playing running back, has been super beneficial for me. Last year, I kind of had to learn on the fly and I was put in a position where I could make a couple plays. I’m grateful for that.
“Having a full spring ball, a full offseason, to gain some weight and learn more about the offense has been really good for me as a running back,” he continued.
Asked about how Sione Moa is coming along after last year’s compartment syndrome injury, Roderick said the redshirt sophomore “looks great” and called Moa “one of the best athletes on the team,” and then praised Rex.
“I am really excited about the improvement that Preston Rex has made since last year,” Roderick said. “He got thrown into a tough situation. He wasn’t really a running back, and he had to learn to play it on the fly, and he did make some good plays for us last year in the open field.
“With a full offseason, he really looks more like a running back now and really looks like he knows what he’s doing,” Roderick continued. “And then (freshman) Devaughn Eka has done some great things. Devaughn Eka will play this year. He will get some playing time. He’s been impressive, yup.”
Rex also had high praise for Eka, calling the Lehi High product a potential fan favorite. He said another RB to keep an eye on is Logan Payne, son of former BYU kicker and punter Matt Payne.
“Both those guys are ballers,” Rex said. “I’m excited for those younger guys to get their shot this year as well.”
Another Rex is also on his way to BYU; versatile athlete Jaxson Rex, who is Preston’s cousin, committed to BYU in June and will also play for San Clemente High this fall.
