Mariners reportedly shoot down Red Sox trade offer for powerful first baseman

Seattle hasn't done much other than sit on their hands this offseason. They did pick up an old flame from the Rays, but that will hardly move the needle heading into 2025. To make matters worse, the front office doesn't seem to be as active as many fans hoped, citing their strong faith in the current roster.

Despite their unwillingness to pursue any serious conversations, other teams have attempted to acquire some of their most prized assets, particularly pieces of their starting rotation.

The latest suitor was the Boston Red Sox, who reportedly offered to trade Triston Casas in exchange for either Bryce Miller or Bryan Woo. Sidelined for much of the 2024 season with a fractured rib, the value of Casas is largely based on his successful 2023 campaign, during which he posted a 129 OPS+ and placed third in AL Rookie of the Year voting. He has the profile of a typical first baseman: a crippling lack of speed, poor fielding ability, average swing decisions, and demonstrable power. His quality of contact numbers for 2023 were outstanding, placing in the top quartile for every metric other than launch angle sweet spot. He also has an elite career walk rate of 14.2%, up there with other masters of plate discipline like Kyle Schwarber (14.1%) and Jesse Winker (12.8%). Despite this, his whiff and strikeout rates were still below 30%, giving him better results at the plate than other big boppers around the league.

So if the Mariners need an impact first baseman, why weren't they receptive to this deal? It all stems from Dipoto's aforementioned optimism. When asked about the future of Luke Raley, he stated that he plans on splitting his time between right field and first base. To his credit, Raley was the fourth-most valuable player on the team by rWAR (3.2) and was the best qualified hitter on the team by OPS+ (129). To Dipoto, a more sensible decision would be to find a platoon partner for Raley at first base against left-handed pitching since southpaws held him to just a .570 OPS over 82 plate appearances in 2024.

Acquiring Triston Casas would mean committing to him as the full-time option at first base, especially given his defensive limitations and the existence of a full-time DH in Mitch Garver. Even picking him up off of waivers may be a tough call given the logjam in the roster, so trading away one of the bright spots of the team's future to bring him to Seattle seemed like an even less prudent decision.

In fact, outside of Luis Castillo, the front office doesn't seem like it will even entertain offers to pick off one of their young starters. Thus, the Mariners will have to keep looking elsewhere for infield assistance. If they don't want to trade any of their major-league talent, perhaps a prospect package could give them the tools they need to return to the playoffs in 2025.