Rosen, the No. 10 overall pick in the 2018 draft, should step in as the Dolphins' Week 1 starting quarterback -- much to the dismay of journeyman Ryan Fitzpatrick. But is he the long-term answer to a franchise quarterback question that hasn't been properly answered since Pro Football Hall of Famer Dan Marino retired?
My guess is no, but the Dolphins believe it's worth the swing. And make no mistake, the Dolphins are rolling the dice on Rosen being their franchise quarterback of the future.
Dolphins general manager Chris Grier deserves credit for capitalizing on Rosen's diminished value while keeping his options open of adding another signal-caller in the 2020 draft.
Grier didn't hold the Arizona Cardinals over the fire in Friday night's trade despite his leverage advantage -- a late second-round pick and a 2020 fifth-round pick aren't throwaways for a team in desperate need of building blocks -- but the value for a recent top-10 pick at the most important position on the field was too good to ignore.
So should Dolphins fans throw away their "Tank for Tua" shirts? Not yet, but they might want to bury them in the closet and purchase some "Chosen Rosen" gear.
It sounds as if first-year Dolphins coach Brian Flores and offensive coordinator Chad O'Shea were the difference-makers in the Rosen deal. That means Rosen has two of the people most integral to the team's success as believers in him.
That's a dramatic change from one year ago. Two sources told ESPN that Baker Mayfield and Josh Allen were the two quarterbacks Miami preferred in the 2018 draft. Each went before the Dolphins' pick, as did Rosen at No. 10, but he wasn't an option in the draft room.
So what changed?
"I wouldn't say we didn't like Rosen," Grier said. "Again, working with different coaching staffs and what they're looking for at the position. At that point, we were talking about a top-10 pick, and he just wasn't in those top five or six guys we were comfortable taking at pick 11."
The Dolphins didn't have a top-11 grade on Rosen, and Adam Gase -- the previous head coach -- wasn't a fan of the former UCLA QB.
"We talked and did a lot of background checks in terms of people in and around Arizona's organization, UCLA's staff that had him and we had the information on him last year, too," Grier said. "Again, we felt comfortable for the value where he was."
Let's not sugarcoat it, Rosen was bad in 2018. His offensive line was arguably the worst in the NFL, the coaching staff was fired and he wasn't provided with a great chance to succeed in Arizona. But Rosen himself was still bad. He had the NFL's worst passer rating, a 55 percent completion rate and 11 touchdowns compared with 14 interceptions.
Miami might be hoping to duplicate the Jared Goff revival plan. Goff had an extremely rocky rookie season with the Los Angeles Rams before turning around his career thanks to the arrival of coach Sean McVay and an improved cast around him.
Maybe O'Shea and quarterbacks coach Jim Caldwell can work wonders for Rosen the way McVay did for Goff, but they certainly have their work cut out.
The Cardinals had the worst pass block win rate (38 percent) in the NFL last season. But the Dolphins had the second-worst pass block win rate (40 percent). So that element will need to be fixed for any sort of turnaround.
ESPN's pass block win rate measures the percentages of dropbacks that an offense holds its blocks for at least 2.5 seconds. It is powered by NFL Next Gen Stats.
So Rosen will have to rebound on a rebuilding team with a roster not much better than Arizona's last season. But maybe a fresh start will be enough for Rosen, whom Grier praised for his intelligence and arm talent, to make a jump in Year 2.
Not everyone has given up on Rosen. Cardinals star running back David Johnson posted a comment on Rosen's celebratory Instagram post Friday night predicting Rosen would "be one of the best when it's all said and done."
Miami hopes Johnson is right. It would be a great coup for the Dolphins to nab their franchise quarterback for a second-round pick and a 2020 fifth-round pick. They also got him at $6.24 million over the next three years with a fifth-year option.
If Rosen doesn't convince the Dolphins he's their guy, then it could lead Miami to go all-in on another quarterback in next April's draft. But is one more season enough to decide on Rosen?
Questions about Miami tanking should dissipate, but the question about the Dolphins' long-term quarterback plan is still in flux. Rosen is a candidate to fill that role, if Miami can fix him.