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 locked in at shortstop but little certainty around the rest of the diamond. First base would likely be occupied by a platoon of and , 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. 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 impre sive versatility and struggles against same-handed pitching. , , and 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 theyve long resisted pulling the trigger on: trading from their vaunted starting rotation. Theres an argument to be made that Seattle boasts the best starting rotation in baseball. , , , and form the sort of proven, controllable corps of young starters that most teams can only dream of developing, and veteran right-hander has served as a veteran anchor for the clubs 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, theyve 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. Thats not to say a Castillo trade comes without potential obstacles. While the right-hander has pitched well during his two full seasons in Seattle, hes 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, Castillos 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; would likely be the next man up if Castillo was dealt, but he struggled in 12 starts last year and theres 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? Lets take a look at nine po sible options, listed alphabetically between three tiers: Best Fits: Blue Jays: The Blue Jays have had a difficult offseason so far, as theyve struck out on both and in free agency. Their biggest addition to this point is infielder , who they swung a deal to acquire from the Guardians during the Winter Meetings. With that said, theyre known to be in the market for starting pitching help, and Castillo would form a solid veteran nucleus in the rotation alongside , , and . Whats more, the Jays have a number of interesting young infielders like , , and who could be of interest to the Mariners. Giants: The Giants made a big splash just before the Winter Meetings began by signing but join Toronto in being a top reported suitor for Burnes who mi sed 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 at the front of San Franciscos rotation, and the Giants have previously expre sed a Tristan Thompson Jersey first baseman this winter. Wade, 31 on New Years 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 hes 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 2023s staff ace isnt expected to pitch in the first half of 2025 following UCL surgery last year. Castillo would slot in front of and 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 and perhaps even add in a young starter like to help replace Castillo in the Seattle rotation. Notably, the Orioles are among the teams that have reportedly the right-hander this winter. Next Tier Down: Braves: The Braves watched both and depart from their rotation for free agency last month but have yet to make a significant move this offseason outside of trading away to the Angels. Adding an arm like Castillo to the mix behind and (eventually) would offer the club another high-end starter while also providing security to a rotation full of frequently injured hurlers. Atlanta doesnt have much to offer in the way of infield help outside of prospect but could help supplement the Mariners rotation by offering a controllable starter like or as part of the return. Cubs: The Cubs have already been to Castillo this winter and are known to be in the market for a front-end starter to pair with and , but the clubs recent trade for has seemingly complicated the fit between the two sides. The Mariners are known to have had interest in Cubs second baseman this winter, and the Cubs previously could part with Hoerner and replace him at the keystone with . Since then, however, the Cubs shipped third baseman to the Astros in exchange for Tucker. With Shaw now penciled in as Paredess replacement at the hot corner, the Cubs may be le s inclined to part with Hoerner to bolster the Mariners infield. While a young starter such as or could help facilitate a trade, its hard to imagine a deal for Castillo getting done that doesnt send some sort of infield help back to Seattle. Red Sox: The Red Sox are also among the teams known to have discu sed Castillo with Seattle, and the club specifically attempted to swing a trade involving him, , and that was eventually . Its 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 le ser infield piece such as or to Seattle alongside a young starter like , but now that the Red Sox have brought 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 could be a serviceable platoon partner for Moore at second base, but even adding a young starter such as alongside Lux seems unlikely to entice the Mariners to part ways with Castillo. Mets: The Mets are among the teams that have been to Castillo this winter, but they subsequently rounded out their rotation by adding left-hander . Its at least theoretically feasible that the club could add Castillo and push 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 exce s pieces such as and that would surely interest Seattle. Tigers: Detroit could use a bona fide front-end arm to pair with next season, and adding mid-rotation veteran didnt exactly fill that need. The Tigers also recently signed in a move that pushed youngster to first base, seemingly leaving former first overall pick without a role in the majors. Torkelson would be a high-upside addition whos sure to be intriguing to the Mariners as they search for first base help, but its 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. Jarrett Allen Jersey