6. Jeff Luhnow, Houston Astros, +3.3 games
With a World Series championship roster, Luhnow wisely emphasized quality over quantity in his roster decisions. Only 24 players came and/or went between the ends of the 2017 and 2018 seasons, making Houston something of a sea of tranquility on the baseball landscape. A couple of those moves, though, were major.
Begin with the obvious, the trade for Gerrit Cole to buttress an already-strong rotation. One of only four players to arrive by trade all season, Cole’s 15-5 record and 2.88 ERA in 32 starts must have surpassed expectations; it yielded a +3.4 WAA.
Luhnow’s one regret might be his failure to pursue the re-signing of free agent Mike Fiers, who left for Detroit (and eventually Oakland), where he delivered a 12-8 record and 3.56 ERA in 30 starts, good for +2.2 WAA.
Most of the rest of what Luhnow did in 2018 amounted to tinkering around the edges. His trade deadline acquisition of pitcher Ryan Pressly from the Twins for two minor leagues was a modest (+0.8) benefit, as was his decision to give George Springer a two-year, $24 million deal.
Luhnow used nine first-year farm system products in 2018, but none in front-line roles. The most impactful, reserve outfielder Kyle Tucker and backup catcher J.D. Davis, produced negative WAAs, but neither played enough to be of consequence.