Rosen has been limited to mop-up duty in the Dolphins' two blowout losses. He'll take over for the 36-year-old Fitzpatrick, who's completed just 50 percent of his passes and thrown just one touchdown to four interceptions.
The move allows a rebuilding Miami team to determine if Rosen is its future franchise QB before likely garnering a top-five selection in the 2020 draft, which could include Oregon's Justin Herbert and Alabama's Tua Tagovailoa.
He started 13 games in Arizona, under similar circumstances to his current home, and struggled behind a porous offensive line. Rosen completed just 55.2 percent of his passes for 2,278 yards and 11 touchdowns with 14 interceptions, while leading the Cards to just three wins. He quickly became expendable as Arizona swapped out first-year coach Steve Wilks for Kliff Kingbsury.
Two games later, the Dolphins are going in another direction. Rosen will again be operating behind an offensive line under construction that will test his mobility. He's already been sacked four times despite only making cameos, this after being sacked 45 times as a rookie. He has completed 8 of 21 passes for 102 yards and two interceptions this season.
Rosen isn't the only former first-rounder getting a shot in South Beach. Defensive end Taco Charlton, who was released by the Dallas Cowboys this week, was claimed by the Dolphins on Thursday. In two seasons in Dallas, the 2017 No. 28 overall pick started seven of 27 games played, recording four sacks, 11 QB hits and one forced fumble.