Where Can The Mariners Turn For Third Base Help?

The Mariners haven’t been shy about their desire to shore up their infield mix this winter, and while at points in the offseason the club has shown an interest in upgrading at second their focus appears to be primarily on upgrading the infield corners rather than the keystone, where options like Dylan Moore and Ryan Bliss are available to hold down the fort until top middle infield prospect Cole Young is ready for his MLB debut.

First base appears to be fairly simple hole for the club to fill. They’ve long been connected to a reunion with veteran Justin Turner, who helped to bolster their first base mix down the stretch and could pair well with Luke Raley’s left-handed bat at the position. Aside from that possibility, a number of viable veteran options like Mark Canha and Anthony Rizzo still remain available in free agency as well, not to mention trade candidates like Yandy Diaz, Luis Arraez, and LaMonte Wade Jr. who could provide a bit more impact at the cost of trade capital. Even after a run on first base talent just before the New Year, plenty of options remain available for the club to consider as they look for an upgrade over Raley and youngster Tyler Locklear.

Third base, however, is a bit more complicated. While a number of players could at least theoretically be available at the position this winter, Alex Bregman and Nolan Arenado both figure to be well outside of the Mariners’ price range. Another potential trade candidate, Eugenio Suarez, also seems unlikely to be a fit given that the Mariners themselves traded Suarez just one offseason ago. Beyond Bregman, few options available in free agency provide obvious upgrades over Josh Rojas, who the club utilized at third base last year before non-tendering him back in November.

Standing pat doesn’t appear to be an option at the position, either: Austin Shenton and Leo Rivas could at least theoretically pitch in at the position but have a combined 136 plate appearances at the big league level, necessitating at least one veteran addition to take the lion’s share of reps at the hot corner. With an apparently tight budget and minimal internal solutions available, who could be a realistic target for the club this winter?

Free Agents

• Ha-Seong Kim: Kim, 29, is without a doubt the best free agent infielder who could potentially fit into the Mariners’ budget given his 106 wRC+ and plus defense all around the infield over the past three seasons. MLBTR predicted Kim to land a relatively affordable one-year, $12MM contract ahead of the 2025 season at the outset of the offseason, but as the market has developed some reports have indicated he could land a multi-year deal this winter and depending on how the bidding goes, it’s easy to imagine things going beyond Seattle’s comfort zone. Beyond the possibility of Kim landing a deal that goes beyond what Seattle is willing to offer, Kim has played both shortstop and second base far more commonly than third throughout his career. As Kim likely looks to rebuild his value coming off shoulder surgery, it would hardly be a shock if he preferred to sign somewhere where he’d be able to be a regular shortstop. He’d be a defensive upgrade for J.P. Crawford, but the Mariners have shown no desire to move him off the position to this point.
• Paul DeJong: DeJong, 31, was a quality regular at shortstop with the Cardinals early in his career and even made an All-Star game back in 2019. His offense fell way off after that season, however, and he struggled to a 72 wRC+ from 2020 to 2023. Last season as something of a rebound for the veteran, however, as he split time between the White Sox and Royals and managed to hit a respectable .227/.276/.427 (95 wRC+) in 139 games with solid glovework at both shortstop and, more importantly in this context, third base. That respectable season should allow him to easily beat the $1.75MM guarantee he landed with Chicago last winter, though he should nonetheless still be a perfectly affordable option for the Mariners this winter. It’s easy to imagine DeJong jumping at the opportunity if offered regular starts in Seattle, but it’s fair to wonder if the Mariners would have much interest in him as a fit. After all, they just parted ways with Rojas back in November despite strong glovework thanks to his below average offense, and DeJong’s 32.4% strikeout rate last year goes against the more contact-oriented approach the club has attempted to cultivate in recent years.
• Yoán Moncada: Moncada would be an interesting candidate for the third base job in Seattle. A former top prospect, Moncada has had an up-and-down career with the White Sox before things came off the rails due to injuries the past few years. He’s played just 104 games over the past two seasons, but has a fairly respectable 101 wRC+ in that time. It’s far from impossible to imagine him bouncing back to something closer to the 120 wRC+ he posted with Chicago back in 2021, though it’s possible that (like with DeJong) his elevated strikeout numbers throughout his career could give the Mariners some pause. That said, Moncada’s overall offensive profile when healthy is stronger than that of DeJong’s, and given his limited track record in recent years the infielder should still be very affordable.
• Jose Iglesias: Iglesias is coming off a career year with the Mets that saw him slash .337/.381/.448 (137 wRC+) in 291 plate appearances across 85 games. That’s the sort of performance that should make him a very attractive candidate for virtually any club’s bench mix, but the Mariners could stand out among other potential suitors by offering him a regular role. With that being said, there’s plenty of potential cause for concern in Iglesias’s profile. The veteran infielder will play all of this coming season at age-35, and it’s impossible to imagine him replicating the incredible .382 BABIP that made him an above-average hitter last year. He’s also fairly inexperienced at third base, although he did play the position quite well (+2 Outs Above Average) when called upon by the Mets last year. Iglesias’s contact-oriented approach could hold particular appeal in Seattle, and he could be an attractive option for the club if they’re interested in giving larger roles to youngsters like Shenton and Rivas.

Trade Candidates

• Alec Bohm: Bohm stands out on this list in part because the club has already reportedly expressed interest in his services this winter. Those talks understandably seemed to fizzle out when the Phillies asked for Logan Gilbert or George Kirby in return for Bohm’s services, but if Philadelphia decides to drop their asking price as the offseason drags on he remains one of the better fits available to the Mariners this winter. While Bohm’s defense at the hot corner has generally left much to be desired, he slashed a strong .280/.332/.448 (115 wRC+) last year and struck out just 14.2% of the time, making him a strong fit for a club that has typically shied away from high-strikeout hitters when possible. If the asking price for Bohm stays anywhere near where it was earlier this offseason, however, it’s hard to imagine a trade coming together.
• Willi Castro: Castro, 28 in April, has started just 48 games at third base throughout his career to this point but is a super utility player with a great deal of experience at both shortstop and second base, which suggests he should be able to handle the hot corner relatively easily. Since joining the Twins prior to the 2023 season, Castro has put up back-to-back 108 wRC+ seasons while accumulating 5.6 fWAR. Minnesota seems disinclined to pay the $6.2MM that MLBTR contributor Matt Swartz projects Castro will earn in his final trip through arbitration, but that’s a price tag the Mariners should have little trouble stomaching for a likely regular at a position of need.
• Brett Baty: Baty, 25, stands out from the other potential trade candidates mentioned thanks to the fact that he’s got just 169 MLB games under his belt. A former consensus top-30 prospect in the sport, Baty has struggled to this point in his big league career and hit just .229/.306/.327 (83 wRC+) in 50 games with the Mets this past season. The emergence of Mark Vientos has seemingly boxed Baty out of a path to playing time with the club in 2025, particularly if Pete Alonso eventually returns to Queens. That could make Baty expendable for the club, and if the Mariners aren’t able to find a more reliable veteran option in free agency or on the trade market it would be very understandable for the club to pivot towards rolling the dice on a player with Baty’s offensive potential and prospect pedigree.