On July 14, the San Diego Padres traded starting pitcher Drew Pomeranz to the Boston Red Sox. Pomeranz, 27, is currently in the midst of his first full season in a Major League rotation since 2012, when he had a 4.93 ERA and 4.81 fielding-independent ERA. It was with the Colorado Rockies, but even adjusting for park factors, he was not very good. Pomeranz was a decent pitcher in the last two seasons, but while alternating between the rotation and the bullpen.
And for Pomeranz, already over 100 innings pitched for the first time in his big-league career and seemingly pitching over his head (while there is some reason to believe he has turned a corner of sorts, Pomeranz's 2.47 ERA is in spite of a 3.62 xFIP and 3.72 SIERA), while already into the arbitration stage of his MLB service clock, the Red Sox traded Anderson Espinoza, a minor league pitcher whom Baseball America ranked the #19 prospect in all of baseball before the season.
All of baseball knew the Padres were motivated sellers and knew that Drew Pomeranz was an attractive target for teams hoping to bolster their rotations for the 2016 stretch run. But in the end, the Padres were still able to acquire a tremendous prospect because there was only one Drew Pomeranz and there were many teams courting him.
Aroldis Chapman is in many ways a different prospective trade target than Drew Pomeranz. Chapman is a much safer bet to be productive (in the bullpen rather than the rotation, but productive nonetheless), and his performance on the radar gun is resembling a video game hack more and more by the day. And while Pomeranz still has two more years of salary arbitration remaining, Chapman will be a free agent after this season.
But in both cases, the selling team has all of the leverage. It is even more the case with Chapman, because while Pomeranz may have been unique among realistic trade targets as a fairly young, cost-controlled starter, Chapman is unique among pitchers in baseball, on the market or not. For those unfamiliar with MLB.com's Statcast, which tracks the highest pitch velocities in baseball (among other things), it includes an Aroldis Chapman filter, because the top of the velocity leaderboard is so bogged down with his heat.
Without question, Aroldis Chapman would improve the bullpen of the St. Louis Cardinals. Even looking beyond just his incomprehensible fastball speed, he has been the third most valuable relief pitcher in baseball this decade by Fangraphs Wins Above Replacement, trailing only Craig Kimbrel and Kenley Jansen while trailing each by over 30 innings. He isn't just a sideshow; he's an extraordinarily effective relief pitcher.
The Yankees have the option to continue their own run at the 2016 playoffs with Chapman (their odds of winning a Wild Card berth are firmly in the single digits, and their odds of winning the AL East are even slimmer, but given the Yankees' history of refusing to sell at the trade deadline, this may be enough to inspire them to hold, if not buy). And at the end of the season, the Yankees can give Aroldis Chapman the qualifying offer. The qualifying offer is a rare move for relievers, though the Yankees were willing to give one to David Robertson, who is not as good of a pitcher as Aroldis Chapman.
Regardless, barring catastrophic injury, the floor of the return that the Yankees would get for Aroldis Chapman (assuming he does not wind up with the Yankees again next year, at least) would be a first round pick received from a team signing Chapman in the off-season. The Yankees are not going to give away a player, even if they concluded he had very little use to them for the remainder of 2016, if he can provide what will certainly amount to a worthwhile prospect once he is drafted in June 2017.
Chapman would be a lower cost option than another Yankees reliever, Andrew Miller. Viva El Birdos sister site Pinstripe Alley has admitted as much in evaluating potential trades between the Yankees and Cardinals. But he is cheaper for a reason, which is that he would provide much less value over the course of his much shorter tenure with the Cardinals. You get what you pay for, but because many other teams would happily pay for Chapman (again, he is a great pitcher), the cost increases.
John Mozeliak has been willing to trade high-ish ranked prospects at the deadline for lesser veterans in the past, but in return for trading Zack Cox or Rob Kaminsky (at the time among the best prospects in the organization), the Cardinals received Edward Mujica and Brandon Moss. Rather than dealing for pure rentals, the Cardinals hedged their bets by trading for players intended to improve the team both in the short term and in the next season.
Of course, with Chapman, it is impossible to ignore his involvement in a very disturbing domestic violence incident within the last year. Sports fans in general tend to have flexible morality of these things (having rooted for an NFL team that employed Leonard Little for over a decade after pleading guilty to involuntary manslaughter, I won't claim to be exempt from this). I don't think rooting for teams that employ bad people makes you a bad person (although I can certainly do without stories of on-field success being treated as examples of actual human redemption); it's simply the logical conclusion of the completely illogical sports fan tendency to root for the abstract concept of a "team" rather than for or against the actual human beings which comprise it.
Adding the element of personal discomfort shouldn't be a non-factor for Cardinals management; acquiring Chapman wouldn't cause attendance to crater or anything like that, but it would certainly give many fans the kind of discomfort that can have a cumulative effect on one's degree of passion for the team.
But even if Aroldis Chapman had an immaculate personal record, the Cardinals still shouldn't trade for him. He is still a two month rental (and keep in mind that a mid-season trade would make him ineligible for a qualifying offer anyway) for a playoff run which is hardly assured to be successful even with the acquisition of a top-line reliever. That Chapman's presence would additionally be problematic for non-baseball reasons just drives home that this is a move that definitely should not happen.