In today's baseball, there's no rivalry quite like the one between the Yankees and the Red Sox. They're two of the three best teams in the American League, and both have young cores capable of sustaining the rivalry for years to come. What's more, the Yankees and Red Sox both have significant financial resources, meaning that they should be involved in an arms race to secure the best available talent and match each other's move every offseason.
Last winter, that arms race consisted mainly of two names - Giancarlo Stanton and J.D. Martinez. Two of baseball's most fearsome sluggers joined two of baseball's most fierce rival clubs. Now the question on everyone's mind is, which team made the better deal? My take is that the Yankees got the better player, emphasis on player.
Now, my take might be counterintuitive, considering how Stanton and Martinez have played to this point. Stanton has struggled to meet the lofty expectations of Yankees fans, posting a .248/.324/.476 slash line with 12 homers for a 114 wRC+. Meanwhile, Martinez has been on fire for the Red Sox, hitting .318/.379/.664 with 19 dingers and a 174 wRC+. If you like fWAR, it suggests that Martinez (2.1 WAR) has been almost twice as valuable as Stanton (1.1) in the early goings. No matter how you slice it, there's no question that Martinez has been hands down the better performer so far.
Stanton, however, has more going for him than you'd think when you look at the overall package. While underperforming at the plate, he has been a net positive because he can run the bases and hold his own in the field, accumulating 0.1 baserunning runs and 0.8 defensive runs so far. This isn't a fluke, as his career numbers suggest that he's been a slightly below-average baserunner and an average fielder once you factor in the positional adjustment.
If you prefer the eye test, just think of all the times you've seen him beat out infield singles so far. I'm not saying all those weak grounders are a good thing, as I'd much rather watch him generate fly balls with more consistency. It’s still a testament to Stanton's athleticism that he can bust it down the line and make it to first base safely on infield hits. Nobody's going to mistake Stanton for Billy Hamilton on the bases or Kevin Kiermaier in the field, but it's not like he's a one-dimensional slugger, either. As power hitters go, he's a well-rounded athlete.
Martinez, on the other hand, is the epitome of a one-dimensional slugger. While he's accumulated 106.8 offensive runs so far in his career, he's also compiled -21.8 baserunning runs and a whopping -52.8 defensive runs. Granted, value is value no matter how you create it, and Martinez more than makes up for his atrocious baserunning and glovework by hitting the snot out of the ball at the plate. But Martinez has been so bad in the non-hitting aspects of the game that even though he's outhit Stanton in terms of wRC+ in each the past two years, Stanton has generated more fWAR in the same time span, 8.2 to 5.9.
So, while it is true that Martinez has significantly outhit Stanton so far, he lags behind him in terms of baserunning and fielding. Should Stanton get into one of his patented hot streaks, he should make up the gap between him and Martinez pretty easily. Looking to the future, I'm pretty sure that Stanton, an athletic 28-year-old, albeit with some health concerns in the past, will be able to age more gracefully than Martinez, who will be 31 this season and has had health troubles of his own. Despite the gap in performance so far, I'm still confident that the Yankees got the better player.