The Red Sox have a brand new closer, and he was the best one available. Maybe you like Aroldis Chapman better, and that's fine, but Chapman is signed for one year: Craig Kimbrel can be with the Red Sox for the next three, as he has two guaranteed years and a reasonable 2018 option in his current contract. Yes, he was expensive in terms of the prospects it took to get him, but that's only a negative if you assume some best-case scenario futures for them, and ignore that the Red Sox are setup to win now and in the future thanks to Kimbrel.
Manuel Margot is and will likely stay legitimate: he's a center fielder who projects to play above-average defense (or maybe better) in the majors, run the bases well, and even if the 21-year-old never develops any real power, he can still be a productive hitter thanks to his skill set. He's also possibly the only one that Red Sox fans might miss, and if that's the case, they'll remember that the price for that was one of the best relievers in the game.
Logan Allen, drafted just a few months ago in the eighth round by the Red Sox, has a potentially bright future. He was one of the picks that made Boston's draft seem more exciting and with a higher ceiling. He is also just 18 years old, though, which in prospect terms, makes him something of a formless blob that is yet to be shaped. He might turn out to be great: he might also get hurt, or never quite put it together, or develop but become less than what his greatest future could be. We know what Craig Kimbrel is, and we know what these current Red Sox needed -- even if Allen turns out to be a thing, it won't be for years, and the plan is for Boston to win before that time with the core they have.
Carlos Asuaje might turn out to be a useful utility man in the majors someday. He has some patience, he has some skill in making good decisions at the plate, and he's a solid defender at multiple infield positions and recently took to the outfield in preparation for his future. You don't let a potentially useful utility player step in the way of acquiring Kimbrel.
The same goes for Javier Guerra, who is a very different player than Asuaje, but still comes with the same kind of questions that should keep you from hugging him too close at the expense of the present. Guerra showed some serious power this summer as a 19-year-old shortstop in Low-A, but his offensive outburst was also a huge surprise, as he's been considered a glove-first player. Guerra wouldn't be the first to succeed in the low minors offensively then tail off against more talented competition -- he also wouldn't be the first to sustain an unexpected burst of development and become better than he was ever expected to be.
He's promising, and he could be a serious player someday, but you have these players either to promote them or to use them in trades to find the ones you can't produce yourself. Kimbrel is a player the Red Sox cannot produce themselves, and at a time when they need someone like him.
Don't let any of this let you forget that yes, the Red Sox gave up a whole lot of talent. Margot, Guerra, Allen, and Asuaje could all be key pieces on a competitive Padres team in the future. The thing is, Craig Kimbrel is going to be a major piece on a competitive Red Sox team right now, as the bullpen was a major part of what held them back in 2015. And let's not forget that Boston, unlike the Padres, didn't have to take Melvin Upton and his contract back in order to get Kimbrel -- if you're noticing a prospect discrepancy in these two trades, he's the reason why.
Kimbrel has given up five hits per nine for his career. He struck out over 13 batters per nine in 2015, and whiffed four times as many as he walked. His 2.58 ERA was the worst of his six-year career -- the Sox would be pretty happy with a few more "worst" campaigns like that one. Remember, too, that ERA for a reliever can fluctuate wildly thanks to just a couple of outings: Kimbrel's ERA from 2012 through 2014 was all of 1.27, with the right-hander striking out 42 percent of the batters he faced.
He's owed $11 million in 2016, and $13 million both for 2017 and his option year of 2018. His average annual value is just $10.5 million -- less than what Jonathan Papelbon made on a deal he signed after 2011. He's arguably the game's best closer, and if he's not the best, he's second or third.
The Red Sox feature a bullpen with a 41-year-old closer who has missed time with injury often and whose workload needs to be managed. Their primary setup man, Junichi Tazawa, was run into the ground in 2015 because there was no one else to stop opposing lineups on the bridge to Koji Uehara. Kimbrel will get Koji back to a setup role, and that will relieve some of Taz's burden: the Sox also don't need to be done upgrading their bullpen, either, as free agents like Joakim Soria, Darren O'Day, and Ryan Madson are still out there.
Maybe you think this is too much to give up for a reliever. And hey, it might end up being that way: again, all of these prospects could hit their best-case scenarios, and the Sox aren't guaranteed to win a thing. With that being said, the bullpen is a major part of a team. Boston's threw 501 innings in 2015, and produced a 4.24 ERA: the league-average ERA for a bullpen was 3.71, meaning Boston's starters -- yes, even with Justin Masterson and Rick Porcello's first-half disaster and Wade Miley's April and Joe Kelly, starting pticher -- were closer to their league-average than the relievers were: the Sox rotation was at 4.39 while the league was at 4.10. Boston's rotation pitched well more often than most people noticed, and it's largely thanks to the bullpen that their performances went unrecognized. Kimbrel can help Boston avoid a repeat.
Improving the bullpen and improving the defense are the real keys to the Red Sox turning things around. Kimbrel helps with the former, and even with the latter to a degree thanks to his absurd strikeout rates. Yes, he cost the Red Sox four prospects, at least two of whom have real chances to be somebody in the majors someday. They still have Yoan Moncada, though. They still have Andrew Benintendi. They still have Anderson Espinoza, Rafael Devers, Henry Owens, Michael Kopech, and the major-league foursome of Xander Bogaerts, Mookie Betts, Eduardo Rodriguez, and Blake Swihart.
Dave Dombrowski did not give up on youth or prospects or anything of the sort. He leveraged Boston's depth into acquiring one of the great closers out there, one who will help in the ninth inning and with his presence alone will help improve the quality of Boston's seventh and eighth innings. And he'll do that for three years.
It might seem expensive, but the Red Sox have a real chance to win now in a division with no real identity -- the Blue Jays, Orioles, Rays, and Yankees are all in various states of flux. Kimbrel isn't Aroldis Chapman -- he's not some rental who cost the Sox dearly in prospects. He's going to be a major part of this team for three years, and a whole lot of things could go Boston's way in that time. And maybe even before any of the four prospects dealt produce much of anything for the Padres.