In exchange for Smyly, the Rays received outfielder Mallex Smith (whom the Mariners acquired earlier in the day), infielder Carlos Vargas and left-handed pitcher Ryan Yarbrough.
Smyly will fill out the 2017 Mariners' rotation, a group that will look quite different after an offseason full of moves from general manager Jerry Dipoto and company.
Now, the projected rotation for next year still features Hernandez, Iwakuma and James Paxton, but Yovani Gallardo and Smyly were added on at the back for depth. Both have the opportunity to provide real upside.
Like Gallardo, Smyly will be moving from a hitter-friendly AL East to a much more pitcher-favorable AL West division. The Mariners will represent his third team in just six big league seasons (2017 will be his sixth), and he has had a wide array of success.
Smyly made his first 30+ start season in 2016, posting a 4.88 ERA and a 167-49 strikeout-to-walk ratio over 175.1 innings. His FIP (4.49) and xFIP (4.51) suggest that he was better than his ERA but not by much. Still, though, he provided value and was worth 2.0 fWAR.
Smyly was the 68th overall pick in the 2010 MLB Draft by the Tigers and will be a free agent following the 2018 season. He was once a semi-highly regarded pitching prospect and has shown flashes of dominance throughout his big league career but has not been able to put it altogether over the course of a full season.
The risk associated with Smyly, though, appears to be worth it for the Mariners, who won 86 games in 2016 and appear to be in prime position to make the playoffs in 2017 for the first time since 2001.
Smyly did not come at a cheap price, though.
The 23-year-old Smith is the headliner in the return for Tampa Bay. Making his big league debut in 2016, the former Atlanta Brave hit .238/.316/.365 over 215 plate appearances. A former 5th round pick, Smith was rated as the Braves' 17th-best prospect before losing rookie status.
Vargas, 17, posted a .734 OPS in 256 plate appearances in Rookie ball last year. Yarbrough, 25, posted a 2.95 ERA and a 99-31 K/BB ratio in 128.1 innings in Double-A. They also head to the Rays.