With Castillo Secured, Mariners Upgrade at Margins With Casali, Boyd, and Lamb

After getting ahead of the trade deadline frenzy by acquiring Luis Castillo on Friday, the Mariners spent Tuesday adding some depth around the roster, picking up Curt Casali and Matthew Boyd from the Giants in exchange for a couple of minor leaguers, right-handed reliever Michael Stryffeler and catcher Andy Thomas. In a separate deal, they also grabbed Jake Lamb from the Dodgers for a player to be named later or cash considerations.

Last week, Justin Choi broke down the adjustments that have led to a breakout season from Seattle’s full-time catcher Cal Raleigh. His excellence this year has helped the Mariners to a cumulative 1.6 WAR from their backstops, the 12th-highest mark in the majors. Unfortunately, nearly all of that production and then some has come from Raleigh alone. Luis Torrens has been the primary backup and one of the worst players in the majors this season, accumulating -0.7 WAR across 42 games. A year after hitting 15 home runs and putting up a 101 wRC+, he has sunk to a pitiful .208/.262/.225 slash line (46 wRC+) without a single home run, which is awful even by the lower standards for catchers.

With Tom Murphy sidelined for the year with a shoulder injury and no other options in the organization, Torrens’ struggles have forced the Mariners to ride Raleigh pretty hard. Since being recalled from Triple-A on May 7 following Murphy’s injury, he has played in 65 of Seattle’s 76 games, starting 55 of them, and has gotten exactly one full day off since June 24, when he sat out the second game of a double-header on July 13.

Casali is currently on the IL after suffering a strained oblique in early July but is in the middle of a rehab assignment and should be activated soon. When healthy, he has been a perfectly serviceable backup backstop for the Rays, Reds, and Giants, accumulating positive WAR in every season of his career except for his rookie campaign back in 2014. Over the last two seasons in San Francisco, he’s put up a .218/.317/.357 slash line (89 wRC+) and 0.8 WAR. He strikes out a little too often but has some power and can take a walk, and he’s a capable defender behind the plate, earning positive framing marks over the last three seasons, though that skill has fallen off a bit this year, down to -2.9 runs in just over 300 innings behind the plate. His familiarity with Castillo from his time in Cincinnati was also a big factor in acquiring him.

In Boyd, the Mariners get another player who is currently on the IL; he’s rehabbing a flexor tendon injury in his throwing elbow suffered last September. Before that, he was a solid member of the Tigers’ rotation, putting up his best season in 2021, when he posted a 3.89 ERA and a 4.10 FIP in 15 starts. That came with a significant home run problem, though, with the lefty allowing 1.62 home runs per nine innings between 2017 and ’20. Even in 2019, when he posted a 30.2% strikeout rate, he was undone by a whopping 39 home runs surrendered in 185.1 innings. Last year, he reduced the number of four-seam fastballs in his pitch mix, which could explain part of why his HR/9 rate fell to 1.03, though the switch to a deadened ball last season might have also played a role.

Once Boyd heals from his elbow injury and returns to the majors, the Mariners plan to use him as a multi-inning reliever out of the bullpen. More length and depth is particularly useful for Seattle, which now has a frontline starter for a playoff push in Castillo but also has young pitchers who are close to hitting their innings ceilings. George Kirby has thrown a combined 100 frames between the majors and the minors this year after throwing just 67.2 last year, and Logan Gilbert is just about to surpass his innings total from last year (124.1). It wouldn’t be surprising to see the Mariners use Boyd as a piggyback for either one of those pitchers as a way to keep their innings in check down the stretch.

The prospect cost for Casali and Boyd was fairly light. Stryffeler was one of the fringe prospects listed by Eric Longenhagen when he looked at the Mariners’ 40-man roster crunch. The righty has posted fantastic strikeout numbers at every stop in the minor leagues since signing as a non-drafted free agent in 2019; his swinging-strike rates have been among the highest in the organization over the last two years. Thomas was a fifth-round pick in last year’s draft and has quickly moved through Seattle’s system. With High-A Everett this year, he’s posted a .264/.400/.444 slash line (145 wRC+) and shown both a solid approach at the plate and decent power.

Lamb signed a minor league contract with the Dodgers this spring and was called up in late June. Despite bouncing around six different organizations since 2020, he enjoyed a bit of a resurgence in Los Angeles, posting a .239/.338/.433 slash line (121 wRC+) in 77 plate appearances. It’s his highest level of production since 2016–17, when he was a key member of the Diamondbacks, slugging 59 home runs across those two years. Sample size caveats aside, he’s posted career-best 11.6% barrel rates over the last two seasons, and a bunch of his hitting peripherals have seen a rebound after they fall apart in ‘18 and ‘19. His late-career improvements stem from a rebuilt swing geared toward helping him catch up to high velocity again, as detailed in a preseason profile by The Athletic’s Fabian Ardaya:

[Lamb] changed his setup, getting more into his legs as he stood at the plate. The leg kick that was so out of whack locked into a solid rhythm to generate force, allowing him to be balanced and be on time. As his bat comes off his shoulder now, his hands are higher to trigger a mental cue to attack elevated pitches. Given the natural loft to Lamb’s swing, he tends to focus on getting on top of pitches rather than generate even more air underneath them. With it, his ability to drive the ball to all fields rather than pulling the ball got easier. His bat entered the zone sooner, and stayed longer and flatter, which reduced the risk of swing-and-miss.

With Joey Gallo essentially taking Lamb’s place on the Dodgers’ roster and a few other players slated to return from the IL soon, that made him expendable. He’ll immediately be asked to help fill one of the biggest holes on the Mariners’ roster: designated hitter, where they’ve received an astonishing 57 wRC+, the lowest mark in the majors, from 15 different players. When they’re all healthy, Ty France, Carlos Santana, Jesse Winker, Kyle Lewis, and Mitch Haniger are slated to fight over four lineup spots: first base, both corner outfield spots, and DH (and you can add Jarred Kelenic to that list of players if he’s able to stick in the majors after his most recent call-up). The problem has been keeping that group of players healthy; hence Abraham Toro and his 49 wRC+ leading the team with 78 plate appearances at the position. Lamb won’t solve all of those issues on his own, but he is a nice left-handed bench option to use this season and should push Toro off the 26-man roster to Triple-A, where he can hopefully figure out his issues.

Adding Castillo is the trade that will move the needle the most for the Mariners, but these additions on the fringe of the major league roster should help them weather whatever attrition they encounter down the stretch. All of them should play a part in Seattle’s quest to end its postseason drought.