4. Brian Cashman, New York Yankees, +4.6 games
The Yankees are famous – okay, notorious – for their excessive use of payroll. So there is at least a small amount of irony to the fact that Cashman’s solid season was built on the most hands-on of all GM skills, straight-up dealing.
He brought 11 players to the Yankees via trades or purchases with other teams, and several played central roles in the club’s push to the post-season. Two minor leaguers plus Starlin Castro landed Giancarlo Stanton from Miami, and Stanton produced +1.7 WAA. When Cashman needed another starter for the pennant push in July, he sent prospects Brandon Drury and Billy McKinney to Toronto for J.A. Happ, who returned +1.5 to the Yankees. Deals with Baltimore for Zach Britton, with St. Louis for Luke Voit and with San Francisco for Andrew McCutchen all also produced positive value.
The short-term impact of Cashman’s trade acquisitions came to +3.5 games, a nifty advance although not nifty enough to make a run at the Red Sox.
The Yankees were comparatively tame players at free agency, their biggest move being the re-signing of C.C. Sabathia for one season at $10 million.
Heralded rookies Gleyber Torres (+1.3WAA) and Miguel Andujar (+0.1 WAA) returned enough positive value to offset the introductory performances of an otherwise so-so cast of farm products, the net amounting to +0.2. If that sounds insufficient, keep in mind that rookies generally do more hurt than harm. The Yankees were one of only 11 teams in 2018 to get a positive impact from their first-year players.