The Rays acquired infield Brad Miller, first baseman and outfielder Logan Morrison and right-handed reliever Danny Farquhar. The Mariners got the likes of right-handed starter Nathan Karns and two prospects: left-handed reliever C.J. Riefenhauser and outfielder Boog Powell.
Four Major Leaguers changed hands in the deal, with Miller, Morrison, Farquhar, and Karns all moving teams.
Nathan Karns likely represents the headliner in this trade. The soon-to-be 28-year-old finished off an excellent rookie year this past season. He posted an 7-5 record with a 3.67 ERA (4.09 FIP) in 147 innings pitched, working to a 145 to 56 strikeout-to-walk ratio.
Karns will add some much-needed depth to the Mariners' 2016 rotation. After the likes of Felix Hernandez and Hisashi Iwakuma in their staff, the Mariners pitched players such as Roenis Elias, Taijuan Walker, and Mike Montgomery, none of whom provided an ERA below 4.00.
Overall, the Mariners' rotation posted a 4.17 ERA, which ranks 17th in the Major Leagues.
New general manager Jerry Dipoto did have to pay the price for Karns, giving up three viable Major League talents in order to acquire him.
The 26-year-old Miller is a valuable asset within himself. Last season, he made appearances at six different positions (excluding DH). For this reason, evaluators compare him to Ben Zobrist, a former Ray who is known for his versatility in the field. Miller's bat posted a .258/.329/.402 slash line in 2015, hitting 11 home runs and driving in 46 RBIs over 497 plate appearances.
Farquhar and Morrison are less prominent acquisitions than Miller, nonetheless, they could still make a legitimate contribution to the Rays through this trade.
The 28-year-old Farquhar had a down season last season, registering a 5.12 ERA, but is just a year removed from a campaign where he had a much more respectable 2.66 mark.
As for the 28-year-old Morrison, this will be his third trade since 2013. He showed promising success all the way back with the Marlins in 2011, slugging 23 home runs and hitting for a .797 OPS, but has failed to build on that since. Morrison's time in Seattle ultimately ended with league-average hitting and below-average defense.
The Rays went for adding to the depth of their team, as they added three pieces to the infield, outfield, and bullpen that should make the team better overall. Miller, in particular, should determine whether they succeeded in this deal or not. He has the chance to add value to the team in many facets of the game.
Lastly, the most underrated portion of this trade is the Mariners' addition of Boog Powell. The 22-year-old reached Triple-A last season and was ranked as the 16th best prospect in the Rays' system by MLBPipeline.com. Powell has shown great ability to hit for average, get on base, and occasionally steal a base. How he develops could really determine how this trade turns out.