THIBODAUX — Josh Rosen’s statistics in his first year at UCLA suggest the transition from California prep powerhouse St. John Bosco to college football in the Pac-12 isn’t all that difficult — at least for him.

He became the first true freshman quarterback to start a season opener for the Bruins, and he had plenty of success in his debut: He completed 28 of 35 passes for 351 yards and three touchdowns in a 34-16 win over Virginia.

He built on that as the year unfolded, throwing for 3,668 yards, 23 touchdowns and 11 interceptions to earn freshman All-America honors. He led the Bruins to eight wins and a spot in the Foster Farms Bowl, where they lost 37-29 to Nebraska.

So the speed, the play calls and the defense — it was just like playing in high school, right?

“We have a great coaching staff at UCLA. The transition was pretty smooth,” Rosen said Friday at the Manning Passing Academy. “But it hurts when you get hit now.”

Rosen came to Pasadena as a five-star prospect and the nation’s consensus top-ranked pro-style quarterback recruit. Instead of throwing him directly into the fire and watching him burn, UCLA coach Jim Mora slowly worked Rosen into the mix during spring and preseason camps.

That decision looked brilliant as Rosen led the Bruins to a 4-0 start. He set the UCLA record for consecutive passing attempts without an interception (245) and set school freshman marks for yards in a game and season.

All of that led him to Thibodaux to work as a camp counselor — something of a surreal experience for the 19-year-old. He grew up watching Peyton Manning, putting him on his Mount Rushmore of great quarterbacks (with Tom Brady, Drew Brees and Aaron Rodgers).

Rosen said he studies the NFL stars’ foot mechanics, release and leadership skills, but he noticed something else in Thibodaux this week.

“What stuck out to me was the Mannings’ demeanor,” he said. “They are very confident, sincere, kind and know who they are. When I talked to them, they gave me their full attention and showed that they cared. The way they walk around the room and command themselves is very impressive.”

Rosen viewed his freshman year as just another season of football, but he has added 15 pounds in the offseason, knowing he needs a little more bulk to make plays outside of the pocket when his protection breaks down. He pointed to his struggles in the Bruins’ 40-21 loss to rival Southern California, when he was 19-of-37 with a touchdown and two interceptions while being sacked three times.

“There are UCLA fans and alumni that would rather lose every game but beat USC, rather than win every game but lose to the Trojans,” Rosen said. “That’s how big the rivalry is.”

After his 2015 breakthrough, Rosen isn’t ready to settle for similar success as a sophomore. He believes he knows what it takes to improve and that hard work will get him there.

His main goal this fall: Win the national championship.

“I will throw for negative yards or break a leg,” he said, “just to play for a national championship.”