Looking For A Match In A Luis Castillo Trade

One of the worst-kept secrets in baseball this winter is the Mariners’ need for infield help. If the 2024 season were to start today, the club would have J.P. Crawford locked in at shortstop but little certainty around the rest of the diamond. First base would likely be occupied by a platoon of Luke Raley and Tyler Locklear, the latter of whom struggled badly in a 16-game cup of coffee with Seattle last year. Second and third base would be even dicier. Dylan Moore is capable of playing both positions and could be an everyday player for the club after appearing in 135 games last year but may be better suited for a super utility role given his impressive versatility and struggles against same-handed pitching. Ryan Bliss, Austin Shenton, and Leo Rivas are all young and intriguing hitters who made their big league debuts in 2024, but none of them got even 100 plate appearances in the majors last year and would be risky to rely on in full-time roles.

That obvious need for an infielder or two has led the Mariners to consider making a move they’ve long resisted pulling the trigger on: trading from their vaunted starting rotation. There’s an argument to be made that Seattle boasts the best starting rotation in baseball. George Kirby, Logan Gilbert, Bryce Miller, and Bryan Woo form the sort of proven, controllable corps of young starters that most teams can only dream of developing, and veteran right-hander Luis Castillo has served as a veteran anchor for the club’s rotation ever since he was acquired from the Reds following the 2022 trade deadline. While the Mariners still seem unlikely to part with any of the youngsters in their rotation, they’ve begun to at least listen to offers on Castillo, who has drawn interest around the league thanks to his fairly affordable contract and consistently above average results.

That’s not to say a Castillo trade comes without potential obstacles. While the right-hander has pitched well during his two full seasons in Seattle, he’s not posted the same front-of-the-rotation results he flashed earlier in his career with Cincinnati. After posting a 3.46 ERA (132 ERA+) with a near-matching 3.43 FIP from 2019 to 2022, Castillo’s 3.48 ERA (110 ERA+) has remained stagnant the last two years despite a much friendlier home ballpark for pitching while his 3.86 FIP is a noticeable step backwards from the earlier days of his career and his fastball velocity has lost a tick or two since he arrived in Washington.

Aside from those potential concerns for would-be suitors, Castillo also wields a full no-trade clause and could block any trade if he so chooses. One final wrinkle from the Mariners’ perspective is their lack of starting pitching depth behind an excellent top five rotation pieces; Emerson Hancock would likely be the next man up if Castillo was dealt, but he struggled in 12 starts last year and there’s virtually no big league ready starting depth behind him in the organization. That could make a team that could offer a young starter in addition to infield help a particularly attractive trade partner for Seattle.

So, which clubs are best suited to swinging a deal for the right-hander? Let’s take a look at nine possible options, listed alphabetically between three tiers:

Best Fits:

• Blue Jays: The Blue Jays have had a difficult offseason so far, as they’ve struck out on both Juan Soto and Corbin Burnes in free agency. Their biggest addition to this point is infielder Andrés Giménez, who they swung a deal to acquire from the Guardians during the Winter Meetings. With that said, they’re known to be in the market for starting pitching help, and Castillo would form a solid veteran nucleus in the rotation alongside Kevin Gausman, José Berríos, and Chris Bassitt. What’s more, the Jays have a number of interesting young infielders like Davis Schneider, Leo Jiménez, and Will Wagner who could be of interest to the Mariners.
• Giants: The Giants made a big splash just before the Winter Meetings began by signing Willy Adames but join Toronto in being a top reported suitor for Burnes who missed out on the right-hander when he agreed to a deal with Arizona late Friday night. Castillo would be an excellent starter to pair with Logan Webb at the front of San Francisco’s rotation, and the Giants have previously expressed a willingness to deal first baseman LaMonte Wade Jr. this winter. Wade, 31 on New Year’s Day, has posted a solid .258/.376/.401 (120 wRC+) with a fantastic 15% walk rate over the past two seasons.
• Orioles: As the team Burnes pitched for in 2024 prior to reaching free agency, the Orioles join the Blue Jays and Giants in the hunt for a top-of-the-rotation arm now that he’s departed for the desert. The need for a front-end arm in Baltimore is perhaps more acute than it is anywhere else on this list, as 2023’s staff ace Kyle Bradish isn’t expected to pitch in the first half of 2025 following UCL surgery last year. Castillo would slot in front of Zach Eflin and Grayson Rodriguez for the Orioles, offering some much-needed stability to the Baltimore rotation. In return, the Orioles could offer a player from their surplus of first base options such as Ryan Mountcastle and perhaps even add in a young starter like Cade Povich to help replace Castillo in the Seattle rotation. Notably, the Orioles are among the teams that have reportedly inquired after the right-hander this winter.

Next Tier Down:

• Braves: The Braves watched both Max Fried and Charlie Morton depart from their rotation for free agency last month but have yet to make a significant move this offseason outside of trading Jorge Soler away to the Angels. Adding an arm like Castillo to the mix behind Chris Sale and (eventually) Spencer Strider would offer the club another high-end starter while also providing security to a rotation full of frequently injured hurlers. Atlanta doesn’t have much to offer in the way of infield help outside of prospect Nacho Alvarez Jr. but could help supplement the Mariners rotation by offering a controllable starter like Bryce Elder or AJ Smith-Shawver as part of the return.
• Cubs: The Cubs have already been connected to Castillo this winter and are known to be in the market for a front-end starter to pair with Justin Steele and Shota Imanaga, but the club’s recent trade for Kyle Tucker has seemingly complicated the fit between the two sides. The Mariners are known to have had interest in Cubs second baseman Nico Hoerner this winter, and the Cubs previously could part with Hoerner and replace him at the keystone with Matt Shaw. Since then, however, the Cubs shipped third baseman Isaac Paredes to the Astros in exchange for Tucker. With Shaw now penciled in as Paredes’s replacement at the hot corner, the Cubs may be less inclined to part with Hoerner to bolster the Mariners’ infield. While a young starter such as Javier Assad or Jordan Wicks could help facilitate a trade, it’s hard to imagine a deal for Castillo getting done that doesn’t send some sort of infield help back to Seattle.
• Red Sox: The Red Sox are also among the teams known to have discussed Castillo with Seattle, and the club specifically attempted to swing a trade involving him, Triston Casas, and Masataka Yoshida that was eventually shut down by the Mariners. It’s hard to imagine Boston parting with Casas in a straight one-for-one swap for Castillo, which could make finding a match between the two sides difficult. Perhaps a deal could still be had that sends a lesser infield piece such as Vaughn Grissom or David Hamilton to Seattle alongside a young starter like Kutter Crawford, but now that the Red Sox have brought Walker Buehler into the rotation other clubs may be more motivated to get a deal done with Seattle than Boston is.

Longer Shots:

• Dodgers: The Dodgers are not known to have interest in Castillo but are always a threat to upgrade their roster and could certainly benefit from adding a steady, innings-eating arm like him to the cavalcade of high-octane arms with durability questions that currently make up their starting rotation. Even so, however, the Dodgers have little to offer from their infield mix at the moment. Perhaps Gavin Lux could be a serviceable platoon partner for Moore at second base, but even adding a young starter such as Landon Knack alongside Lux seems unlikely to entice the Mariners to part ways with Castillo.
• Mets: The Mets are among the teams that have been connected to Castillo this winter, but they subsequently rounded out their rotation by adding left-hander Sean Manaea. It’s at least theoretically feasible that the club could add Castillo and push Clay Holmes out of their projected rotation and into the bullpen, but given the fact that New York explicitly signed Holmes to start that would be a major surprise, even as the Mets have excess pieces such as Brett Baty and Tylor Megill that would surely interest Seattle.
• Tigers: Detroit could use a bona fide front-end arm to pair with Tarik Skubal next season, and adding mid-rotation veteran Alex Cobb didn’t exactly fill that need. The Tigers also recently signed Gleyber Torres in a move that pushed youngster Colt Keith to first base, seemingly leaving former first overall pick Spencer Torkelson without a role in the majors. Torkelson would be a high-upside addition who’s sure to be intriguing to the Mariners as they search for first base help, but it’s unclear whether they would part with Castillo to land him or if the Tigers are interested in taking on the $72.45MM Castillo is guaranteed over the next three seasons.