Rosen joins his third team in as many seasons.
Rosen started three games last season for the Dolphins, completing 53% of his passes for 567 yards, one touchdown and five interceptions. He entered the lineup to replace Ryan Fitzpatrick ahead of a Week 3 game at Dallas, and he was benched during the fourth quarter of a Week 6 game vs. Washington. Fitzpatrick took over at that point, and Rosen didn't get another opportunity to start.
Rosen has a 22.8 Total QBR over his two seasons, last among quarterbacks to appear in at least 20 games in that span.
For Rosen, the question has not been about talent. Miami coach Brian Flores said Rosen had the best arm of all the quarterbacks in camp, but Rosen fell behind when it came to processing -- identifying defenses pre-snap, being able to predict changing coverages and linebackers shifting, and ultimately being able to throw accurately and on time. Those are all skills Rosen has spent time working on this offseason in Miami, and he will look to continue to do in Tampa.
Rosen spent a year working with Tampa Bay offensive coordinator Byron Leftwich in 2018 when they were with Arizona. Rosen credited Leftwich for keeping him steady and on track his rookie season and for breaking things down that he hadn't seen before in games.
By signing with the Bucs' practice squad, Rosen will keep learning, and he can be signed to another team's active roster at any point unless the Bucs designate him as one of four protected players each week.
ESPN's Adam Schefter, Jenna Laine and Cameron Wolfe contributed to this report.