Lourdes Gurriel Jr.
The market on Lourdes Gurriel Jr. was quiet until just a few days ago, when Jon Morosi connected the Red Sox to Gurriel, Michael A. Taylor, and Martin Maldonado. As outfielders, Gurriel and Taylor make sense for the Red Sox, who just traded Alex Verdugo to the Yankees for almost nothing in return. Despite Taylor's elite defense, Gurriel has the edge offensively and is still an above-average outfielder. Gurriel is the only player on this list who the Red Sox aren't known to be actively competing against the Yankees for, and he's a better defensive player than the one the Red Sox just let the Yankees run away with.
Getting Gurriel adds experience and adds a bat that seems to be improving with age. With the Diamondbacks, he had a career-best year in home runs (24) and fWAR, and a near-best year in RBI (82). It's not only a good move for the team in general, it's a way to tell the Yankees that not only did they just receive their problem child, they found a replacement for him that will be better in the outfield and has a comparable bat.