2. Seattle Mariners
The Mariners fell one game behind the Detroit Tigers for the final Wild Card spot this past season. Four players on their roster hit free agency this offseason: first baseman Justin Turner, second baseman Jorge Polanco, third baseman Luis Urias, and relief pitcher Yimi Garcia.
For being so close to the postseason, it is surprising that the offense ranked an abysmal 29th in batting average and 20th in runs per game. The pitching staff carried the Mariners, ranking 1st in ERA with a 3.38 ERA, and the bullpen finished 9th with a 3.71 ERA.
The Mariners' free agency plan is simple, significantly improve the offense, ideally in the infield. The outfield is set with Randy Arozarena, Julio Rodriguez, and breakout star Victor Robles. No one that logged an inning in the infield this past season hit above .240.
The team has $133 million in CBT space, so they have room to pursue top-tier talent. Christian Walker, longtime first baseman of the Arizona Diamondbacks, should be the top target.
He would solidify the cold corner and offer a consistent bat in the lineup. Walker has had over 26 HRs and 84 RBIs in each of the past three seasons, and his .813 OPS in that time would rank first on the Mariners, ahead of even Rodriguez (.801 OPS).
Walker is nearing his mid-30s already, so his contract shouldn't run the Mariners too much, though he is attached to the draft pick compensation after declining the qualifying offer from the Arizona Diamondbacks. As a power-hitting threat with an above-average walk rate (9.7% for his career), he'd provide ideal protection for Rodriguez and Arozarena in the middle of Seattle's lineup.