MOBILE, Ala. — Roger Rosengarten watched Luke McCaffrey travel this path in high school, only in reverse.

When Rosengarten was a freshman and McCaffrey a sophomore at Valor Christian in 2016, McCaffrey played wide receiver and caught a touchdown from his older brother Dylan in a Class 5A state title-clinching victory against Pomona.

By the time McCaffrey was a senior, he had switched to the position he wanted to play all along, and he and Rosengarten had the most sacred of football relationships.

“He was my high school quarterback. I was his left tackle for a year,” Rosengarten recalled to The Post proudly Wednesday evening in a ballroom here, pointing over his shoulder where McCaffrey stood just a couple of first downs away. “We won a state championship and in my opinion, that’s the best Valor team there’s ever been: 13-0 and state champs that year.”

Actually 14 wins, big man, including the clincher against Cherry Creek. All the same, the Eagles dominated and McCaffrey propelled the offense before heading off to Nebraska, where head coach Scott Frost and quarterbacks coach Mario Verduzco were committed to giving McCaffrey a chance to play quarterback.

For two seasons, he did. Even assumed the starting job for a set of games in 2020.

Along the way, though, the Huskers couldn’t help but put McCaffrey’s athleticism to work in other ways. He carried the ball 89 times between 2019 and 2020 and averaged six yards per. He caught a pair of passes, too.

Then he transferred briefly to Louisville before landing at Rice.

In 2021, he played nine games at quarterback (three starts) but it just didn’t click.

Finally, he’d had enough. He decided instead of dabbling at wide receiver, he’d become one.

“When I was at Nebraska, I got to play a little running back, a little receiver, some packages on offense,” he told The Post in the midst of Senior Bowl week. “I always wanted to help the team in any way possible. I think at that time there was a moment where I kind of almost switched. Then, finally, I just kind of wanted to play ball. I wanted to hit people, wanted to go run around, right? Do all the things that it takes to be a ball player.”

He almost immediately proved to be a really good one.

McCaffrey’s exploded over the past two seasons for the Owls. In 2022 he caught 58 passes for 723 yards and six touchdowns, adding another 123 and a score on the ground.

He found another gear this past year, catching 71 balls for 992 yards and 13 scores in as many games to go along with another 117 on the ground (7.8 per carry).

The scary thing: He’s only just getting started.

“I think I’m in the first phase if you were mapping it out,” he said. “It’s a calendar year plus about three months is how long I’ve been playing receiver full-time. It’s been really fun, but it’s still just the beginning phase. I’m excited to keep learning and keep growing.

“Wherever I end up, hopefully I can just embrace the system and embrace helping the team in any way possible.”

He can talk confidently about ending up in the NFL because of the past two seasons. He consistently showed up near the top of National offense’s speed lists by GPS over the week of practice leading into Saturday’s all-star game.

He catches the ball and accelerates up the field without even a consideration of breaking stride. He’s still working on the finer points of route-running and creating separation, but McCaffrey’s got the kind of athleticism his family’s known for.

He’s proved it against some of the country’s best defensive backs here. On Thursday, he caught a dart in the back of the end zone from Washington’s Michael Penix Jr. and his teammates yelled “Luuuuke.”

“There’s no drop-off in every person you go against,” McCaffrey said. “Every one of these guys are studs. It’s a blast to get on the field and do that because that’s how you’re going to learn the best.

“Put your best against another person’s best and seeing where your chips are and then fixing what went wrong and repeating what went well.”

The youngest of the McCaffrey boys has seen a lot go well since he made the transition to receiver. The five years in college might not have gone exactly the way he thought when he headed for college and Rosengarten entered his senior year in high school. Hanging out this week, though, maybe it figures they’re back where they started: Rosengarten — who won a Pac-12 championship with Washington this season — playing up front and McCaffrey catching passes, the future bright for both.

“There’s been a lot of growth and refinement and I’m still in that phase of growth, that initial phase of learning the position,” McCaffrey said. “It’s been so fun and I’m so grateful for (Rice head coach Mike) Bloomgren, (offensive coordinator Marques) Tuiasosopo and (wide receivers coach Mike) Kershaw at Rice. I don’t think this would have gone as well as it has so far without those guys. They’re such a blessing to have in my life.

“They’re some of the best people ever and I think, personally, they changed my life in a lot of ways on and off the field.”

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