Mariners Acquire Josh Lowe for Bryce Miller/Bryan Woo, Cade Marlowe and Trent Thornton
This gives the Mariners the big left-handed bat that they need. Lowe is capable of 20-20 seasons at any point and will probably be a career 270 hitter at his floor. He is most likely a perennial 4-win player that gives you a well-rounded player to slot into the middle or top of the order. Miller or Woo is the cost of acquiring a talent like Lowe, and while Thornton was solid in his time with the Mariners, the Mariners have shown an ability to develop bullpen guys regularly. Plus, there are quite few valuable free agent bullpen pitchers this offseason to spend on, if you save money on the bat.
This gives the Rays a legit #3 starter that has the potential to be a #2 starter in Woo or Miller. I think Miller has a little more trade value, so I think that the Rays would want him, but that difference isn't going to hold up this trade. They get the same control from a starting pitcher that they would from Lowe, so that doesn't really hurt them.
Their pitching staff really struggled to stay healthy, but Tampa Bay's bullpen was actually pretty solid, but being a playoff-contending team, you can never have too many valuable bullpen arms. Plus, this gives them an older outfielder who has hit at every level and may be squeezed out of the rotation in Seattle with Canzone, Kelenic, Julio, Lowe (in this trade scenario) and hopefully, the Mariners acquiring another big corner outfield bat that will rotate at DH.