The Yankees, in possession of a great farm system, have a bevy of trade chips. They pushed a number of those chips into the table this summer. With the team somewhat unexpectedly in the thick of contention, it was prudent to take some future value in the form of prospects and transform it into current, tangible, major league production in the here and now.
Of course, among the trades the Yankees made, two of them were made with the future very much in mind. When they flipped Blake Rutherford, Ian Clarkin, and Tito Polo to Chicago for David Robertson and Tommy Kahnle, it was to build an uber-bullpen both now and in the future. When they sent James Kaprelian, Dustin Fowler, and Jorge Mateo to the Athletics for Sonny Gray, the Yankees wanted to secure a front-line starter for this year as well as 2018 and 2019.
The only trade that was focused solely on 2017 was the Jaime Garcia for Dietrich Enns/Zack Littell swap. So, looking only at the production these new players have provided in 2017 misses a good chunk of the point of these trades. That being said, let's do just that, and look at what the Yankees' midseason deals have done for them in the past two months, to get a sense for how much value they've already recouped in the process.
Let's get the Garcia acquisition out of the way first. Garcia has pitched 35 innings as a Yankee and has allowed 5.14 runs per nine. Baseball Reference estimates that an average pitcher in the same situations as Garcia would have posted a 5.06 RA/9 figure. Garcia has been almost exactly average, reflected in his 0.3 rWAR total.
In the aggregate, Garcia's contributions have probably been a wash; the Yankees haven't much better or worse because of him. As it stands now, with the benefit of hindsight, giving up even lower-level pitching prospects looks like an overpay, albeit an overpay the Yankees were easily willing to make, given their system depth and looming 40-man roster crunch.
The more intersting moves to analyze are obviously the ones where the big names changed hands, starting with the White Sox deal. In Robertson, the Yankees have gotten outstanding production. He's allowed just four runs in 30 innings. His 1.5 rWAR figure is actually the highest among players the Yankees acquired in-season, despite his status as a reliever. Kahnle has carried his weight as well, with a 2.59 RA/9 in 24.1 innings, totaling 0.8 rWAR.
Frazier has also been a big addition. He's hit a strong .218/.366/.424, good for a 114 wRC+. He's rated as four runs above average at third base by Defensive Runs Saved, and thus has totaled 1.3 rWAR. By Baseball Reference's calculations, that's three or four wins the Yankees have added mid-stream with just one trade.
That brings us to the Gray deal. Gray has turned in 54.2 innings with a 3.95 RA/9, good for 1.1 rWAR. So, depending on how you value the players that the likes of Gray and Frazier and Roberstson have replaced (e.g. Garrett Cooper, Caleb Smith, Bryan Mitchell, Givoanny Gallegos, etc), the Yankees have probably added around four or five wins to their 2017 bottom line. That's a pretty impressive boost from a combination of trades that were just as future-centric as they were focused on the present.
How much can we value those added wins? It's not easy to say, given the season isn't in the books, and we don't know what the Yankees would have done had they not cosummated these deals. What we do know is that the Yankees have all but clinched a playoff spot and have remained in the AL East race. They look likely post a win total in the lower-90's, and there's a decent chance they would have ended up in the mid-to-upper-80's had they stood pat at the trade deadline.
In general, wins at the point of the win curve, that upper-80/lower-90 area, are crucial, as they are often the difference between making and missing the postseason. Since one WAR on the free agent market typically goes for over $9 million these days, it's probably safe to say that the Yankees would, on average, value the wins they've added this year at well over $10 million each.
That puts the Yankees well on their way to justifying the cost of their midseason trades. It's impossible to put a precise value on the prospects they surrendered, but in total the price was a little hefty. Rutherford, Mateo, and Fowler all have Top 100 prospect pedigree, while the oft-injured Kaprelian has significant upside. Clarkin and Littell weren't particularly precious prospects but still provide non-zero value.
Yet that the Yankees have already recouped several, high-leverage wins from their deals is huge. The 2017 production that the Yankees have received is not itself enough to justify the trades, but after factoring in the potential playoff contributions their newest players may provide, plus the prospect of Gray, Robertson, and Kahnle pitching in 2018 (and beyond), it's clear that the Yankees' midseason trades are already looking like good investments.
We won't know for years which teams "won" the deals the Yankees particpated in this past July, but it's obvious even two months later that they've receieved ample production. The team would not be in as strong a position without having moved at the deadline, and they are a more dangerous October team thanks to their new additions. Nothing's settled, but so far, the Yankees have to be happy with their early returns.