LOS ANGELES — It’s the toughest transition in sports, or so we are told time after time, season after season. The NFL pocket is no place for a rookie quarterback.

For now — for one fun night in the ancient LA Coliseum — Dak Prescott begged to differ.

The Dallas Cowboys opened the preseason without Tony Romo, Jason Witten, Ezekiel Elliott or Tyron Smith on offense. No one seemed to mind, and virtually nothing slowed down the Cowboys as long as Prescott was on the field.

The rookie from Mississippi State led the Cowboys on three scoring drives for a 24-7 halftime lead. That would have ruined the Rams’ homecoming if their deep reserves hadn’t owned the second half and turned this into a 28-24 LA victory before a fired-up crowd of 89,140.

Prescott completed 10 of 12 passes for 139 yards and two touchdowns. The two incompletions? Both were drops by reserve tight end Geoff Swaim.

Carving up the Rams methodically, this was a low-flying Dak attack.

“In no way did the game seem too big for him,” head coach Jason Garrett said. “Just thought he played with poise and composure.”

On the one hand, it’s an exhibition game, a football friendly, with relatively little at stake. On the other hand, nearly perfect is still nearly perfect. And Prescott looked far more prepared than anyone could have anticipated after two weeks of practice up the road in Oxnard.

Let’s put it this way. No position in sports gets the pre-draft scrutiny of an NFL-bound quarterback. It involves years of tape and then months of workouts, interviews, inspection from head to toe. And, still, scouts never really know.

The quarterback picked at the top of the draft, Jared Goff, made his debut for the Rams and completed four of nine passes for 38 yards. He also threw an interception to Cowboys linebacker Mark Nzeocha.

The quarterback picked No. 2 by Philadelphia, Carson Wentz, went 12-for-24 for just 89 yards with an interception Thursday night. He also suffered a hairline fracture in his ribs that could set him back for a few weeks.

Now it’s just one night, and Goff and Wentz might have Hall of Fame careers ahead of them. Like I said, no one knows. But all we can see is that Prescott — selected 133 picks after Wentz — appears capable of making the transition from college spread quarterback in the SEC to dropback passer in the NFL faster than expected.

“I was waiting for the nervous feeling to come all day, and it never did,” Prescott said. “I think that’s because I was prepared.”

His first pass was dropped by Swaim, filling in for Witten, at the line of scrimmage. It would have produced a short gain. But Prescott was unmoved, hitting his next six passes on the drive with a variety of slants (two to Cole Beasley) and screens before delivering a nifty back-shoulder pass to Dez Bryant just outside the goal line. Bryant reached across the stripe to punctuate Prescott’s first drive with a 10-yard touchdown catch.

“With him playing behind a great leader like Romo, he is going to learn a lot,” Bryant said. “He looked amazing. First time I saw him I thought he looked like a ball player, and that’s what he was tonight.”

Prescott hit two big pass plays on his next scoring drive, a 22-harder to Brice Butler followed by a 32-yard scoring throw to Terrance Williams.

How will the Cowboys choose to view this impressive debut?

Cowboys Owner Jerry Jones has said, following the injury to backup Kellen Moore, that the club would watch the preseason unfold and see what Prescott and Jameill Showers do with the additional work they get in practice and in games.

Showers flashed his potential in the third quarter when he eluded a sack and scrambled to make a 47-yard third-down completion to Vince Mayle. But it’s Prescott’s body of work and the frequently repeated contention that he finds ways to move the football that will get the most examination in the next few days and weeks.

Without Pro Bowl players at left tackle and tight end and the running back expected to transform this offense, it’s hard to call Prescott’s supporting cast “the ones” on that opening drive. But knowing how to get the ball to Beasley and Bryant on their favorite routes gave Prescott an opportunity to shine that most rookies only dream about.

Twitter: @TimCowlishaw