The Red Sox were in the market for relief help, but found their answer in trade rather than having to commit to four years or more for the likes of Kenley Jansen or Aroldis Chapman (to say nothing of the cost). The Brewers did the smart thing by flipping a non-core player with value for prospects, but what they got back is a little underwhelming.

Tyler Thornburg was always miscast as a starter, and the Brewers finally gave up on that experiment for good late in 2015, since which point Thornburg has gone from good reliever to great one. His ultra-high arm slot is all but impossible for a starter, and makes it difficult for him to turn over a changeup, but the two pitches (fastball and curveball) he does have both played up substantially in relief, leading him to the 11th-best strikeout rate (34.2 percent of batters faced) among qualifying relievers in 2016. The high slot makes it harder for hitters to pick up the ball and despite the lack of a third pitch he has never had trouble with left-handed hitters when working in relief. He’s a great setup man for Boston and potentially an alternate closer for when Craig Kimbrel is unavailable or if he should get hurt again, and means that Joe Kelly gets pushed into lower-leverage work and that the Sox aren’t leaning on Carson Smith right away off Tommy John surgery. They get three years of control of Thornburg at his arbitration salaries, which should stay modest as long as he's not racking up more saves.

Mauricio Dubon is the most interesting of the three players coming back to the Brewers, a potential super-utility guy who might be too erratic to be a regular at shortstop but can certainly play it on a part-time basis. He also has spent time at second, third and in center field, where his speed particularly played up in fall league. Dubon has a short, quick swing and solid approach that produces a ton of contact but doesn’t project to more than average power right now. He could be a regular at second or in center, and if he becomes more consistent on defense could be an above-average every-day shortstop, although he may not get that opportunity in Milwaukee with Orlando Arcia a potential star at the same position.

Travis Shaw is a backup, not a regular, who can't hit lefties at all and doesn't even have the OBP skills against right-handed pitching now to compensate for the platoon split, and whose best position is first base. He turns 27 in April and the probability of him becoming anything more than a part-time first or maybe third baseman is slim. Josh Pennington was a 29th-round pick in 2015 as a 19-year-old high school senior from Cape May, New Jersey, now 20 with a good arm but still very inconsistent and more likely to end up a reliever than a starter.

The part of this I find interesting is that rebuilding teams, like the Brewers here and the Phillies last December with Ken Giles, have clearly decided that great young relievers are assets to trade, not to keep. If you’re not winning 90 games, you can dispense with a high-end reliever or closer, and the years of control are less important given the historical volatility of such relievers. (That’s why I’ve noted several times that four-year contracts for relievers are terrible investments. Predicting their performance that many years out, or projecting a great reliever to hold that level of performance for that many years, is sheer folly.) So the Brewers decided to flip a good reliever they didn’t need for some younger players who might fill more important roles. I thought they could have gotten more, given that Shaw was so exposed last year, but the number of free-agent relievers available this winter may have tamped down the market.