The Boston Red Sox got the worst year imaginable out of Wade Miley, and while they're selling low on him right now, they clearly weren't going into 2016 with him in their rotation anyway, so it made some sense to trade him for an asset they'll actually use.

In this case, the Red Sox added a quality setup man in Carson Smith, a low-slot right-hander who destroyed right-handed hitting last year (.169/.248/.254 line with a 38 percent strikeout rate) and gave up so little power to lefties that it mitigated his modest platoon split. I didn't anticipate Smith being that effective against lefties, given his slot and lack of a real changeup, but he has done it for two straight years -- at Triple-A and the majors -- and the last time he had a significant platoon split was in Double-A in 2013 in just 60 plate appearances against lefties.

Smith misses a ton of bats and gets ground balls, and is the Red Sox's best eighth-inning option as long as he keeps getting lefties out, although manager John Farrell has indicated he'll use Koji Uehara as his primary setup man. In any alignment, it's a strong final three for the Red Sox just a year after their bullpen was one of many major weaknesses on the club, and he continues a makeover that has already made the Red Sox better than they were last season.

Boston also adds left-handed starter Roenis Elias, a capable fifth starter who has more feel to pitch than knockout stuff, but whose dominance of left-handed hitters in his two years in the majors -- .218/.304/.332 line, with a 27 percent strikeout rate -- could make him a specialist weapon in relief. The Sox now have four solid starters plus two candidates for the fifth spot in Elias and Joe Kelly, who both project as more valuable assets in relief.

The Mariners give up some certainly in the bullpen to make a bet on Wade Miley's upside, which is unsurprising considering GM Jerry DiPoto and VP of scouting Tom Allison drafted Miley with Arizona in 2008. Miley's 2015 season saw his strikeout rate drop even though he reintroduced his curveball, a useful weapon for him in college, but his other peripherals were fairly steady and pointed to some bad fortune behind the high ERA. Miley is probably a two-win starter in general, which is better than they were going to get out of Elias or Vidal Nuno or Mike Montgomery in the fifth spot, and might even free them up to talk about moving one of the two good young starters -- Taijuan Walker and James Paxton -- other clubs want in any large deal.

Smith fits Boston's needs better than Miley does and has more years of control remaining, but I'd expect Miley to add more value than Smith in any given year. The M's also add a capable middle reliever in Jonathan Aro, a four-seamer/slider guy with a history of low walk rates in the minors but limited upside beyond being an 11th/12th man given his current stuff.