The Beavers joined Fresno State, who offered Rosen during the fall.
By the time he signs a letter of intent in February of 2015, Rosen figures to have his pick of the litter.
This spring, few quarterbacks have looked as good as Rosen has in the early camp and 7on7 circuit.
An all-tournament selection at the NLA Elite 7on7 and all-underclass honors at the L.A. NFTC are just some of the places that Rosen has turned some heads.
And after he led St. John Bosco to their first-ever Trinity League title as a sophomore, his first year as the starter, Rosen is primed for a big couple of years.
Fresno State coach Tim DeRuyter is an alum of St. John Bosco, and the Bulldogs were the first to offer Rosen.
"I had no idea that they were offering me when they did," said Rosen. "They were saying ‘we'd love to have you' and then they offered me," said Rosen. "It all hit me at once that I could do this, go to college and make a run at the NFL. It was sort of a reassurance for me that all this time and effort is paying off."
Oregon State made Rosen his first Pac-12 offer on Thursday afternoon.
"I talked to Coach (Brent) Brennan today, that's who offered and he's a great guy," said Rosen. "Their offensive coordinator is coming in the spring. I definitely have interest and I'm excited to have my first Pac-12 offer. Hopefully this offer will lead to other schools jumping on board. I'm excited to go through the process and see what happens next."
The process has been expedited for Rosen, who first appeared on the radar as an 8th grader when he attended the NLA Elite 7on7 in Las Vegas in March of 2011, and earned all-underclass honors.
Then came another good showing as a freshman in the spring of 2012 and followed by his sophomore season, where he was forced to grow up on the job.
"Honestly, my development really was made by those first two years of middle school and freshman year when (former 7on7 coach) Brian Treggs brought me along," said Rosen. "He got me involved in the 7on7 early and said if you can excel at the NFTC or the 7on7 circuit, it should come naturally as you work through it. Being on the stage I've been as a sophomore, and having people watch it, you become more comfortable in pressure situations. Whether it was rallying against Notre Dame when we were down by two touchdowns are against Jordan, having to run the field in a minute, being put in those situations at a young age makes it easier later on."
With at least eight D-I prospects in the 2014 class at St. John Bosco, including six with offers, Rosen knows plenty of coaches will be around this spring to check them out and to also see him throw.
"I'm kind of bracing myself for the spring, just making sure I'm in tip-top shape and healthy when the coaches come around," said Rosen. "It's not just important for me and my teammates, but for my school to get publicity. The process has been pretty cool. It was a little slow with more of the upperclassmen are getting looks, but I can focus on football and school, and I know that if you take care of what you need on Friday, it will work out. It's great talking with coaches, and I'm still far enough away from that and have a lot to prove."
"I definitely have a very strong idea of where I want to go," said Rosen. "It's been tricky with offseason moves, with Coach (Marucs) Arroyo going to Southern Miss (from Cal) and Coach Pep (Hamilton) to the Indianapolis Colts, and Coach (Ron) Gould leaving for UC Davis. I just have to prove what I need to prove and I believe I can do it."
Rosen said he'll get up to the Bay Area in May, to visit Cal and Stanford and to also camp at the Elite 11 regional.
"I going to go up north again to Cal and Stanford," said Rosen. "I got to meet with Coach Pep and Coach (David) Shaw at Stanford and Coach Arroyo and Coach Gould at Cal and went to the Stanford-Cal game. I had a good time up there."
And he'll also camp at UCLA and meet with the coaches there this spring.
"Coach (Taylor) Mazzone at UCLA reached out to me and invited me to their quarterback and I plan to go to that camp too," said Rosen.
Rosen has two years left to start for St. John Bosco, and while he was thrilled to lead the Braves to the Trinity League title, he knows they came up short in their goal of winning the Pac-5.
"My first two games, I started off really slowly but Coach (Jason) Negro put me in an incredible situation against Santa Fe and just let me throw the ball and it really showed me its not a myth, that poise in the pocket is crucial and I'm going to keep growing from that," said Rosen. "We have a really talented team and we have a goal of winning not just the Trinity League this year but the Pac-5 too."