Matthew Boyd

The Mariners added a backup catcher and strengthened their pitching depth just prior to Tuesday’s deadline, acquiring catcher Curt Casali and lefty Matthew Boyd from the Giants in exchange for minor league righty Michael Stryffeler and catcher Andy Thomas. The Casali and Boyd were initially reported separately but were announced by the teams as part of the same swap. Seattle announced that left-hander Tommy Milone has been released to make room on the 40-man roster for Casali. Boyd is on the 60-day injured list and does not yet require a roster spot.

Casali adds some depth behind Seattle starter Cal Raleigh. The 33-year-old backstop has had a nice showing in limited playing time with the Giants this season. Through 102 plate appearances, Casali is hitting .231/.325/.370, connecting on four homers and a trio of doubles. That’s a nice blend of power and patience from a depth catcher, even when paired with Casali’s typically lofty level of swing-and-miss. He’s also plenty familiar with newly acquired ace Luis Castillo from the pair’s days together in Cincinnati.

Seattle’s No. 2 backstop Luis Torrens has underwhelmed this year, hitting .208/.262/.225 in 42 games. Torrens can’t be optioned to the minor leagues, so Casali’s addition could conceivably squeeze him off the 40-man roster entirely. Raleigh will continue to play most days amidst a breakout season, and the M’s may not want to carry three backstops on the active roster. Casali is currently on the injured list after suffering an oblique strain last month, but he’s on a rehab assignment and should be reinstated to the majors shortly. Casali is making $2.6MM this season, around $928K of which has still to be paid. He’ll be a free agent at season’s end.

Boyd, 31, inked a one-year, $5.2MM deal with the Giants after a mostly solid four-year run with the Tigers. A brutal showing in 2020 skewed his numbers in his final few seasons with Detroit, but Boyd often flashed quality bat-missing ability and typically posted low walk rates throughout his time in the Detroit rotation. He twice looked as though he may be among the more appealing arms available at a trade deadline — first in 2019 when he was sitting on a 3.95 ERA and 152 strikeouts in 114 innings and again in 2021 when he’d posted a similar ERA and reduced home-run rate (albeit with a diminished strikeout rate).

The Tigers held onto Boyd both times, however, declining to move him in ’19 because they (justifiably) set a huge asking price given Boyd’s three-plus remaining seasons of club control. The 2020 season brought little opportunity to move Boyd, thanks to the aforementioned struggles (6.71 ERA in 12 starts), and by the time last year’s deadline rolled around, Boyd’s season was in jeopardy due to that forearm issue.

It’s unlikely that Boyd will be able to return and build up to a starter’s workload this season — but the Mariners, particularly after landing Castillo, don’t really need Boyd to step into the rotation anyhow. He could, however, provide them with an experienced left-hander to plug into the bullpen. Seattle hasn’t had much luck with its left-handed bullpen arms this season, so taking what’s surely a low-cost flier on Boyd is a sensible enough peripheral move at this stage of deadline season.

Stryffeler is a 26-year-old reliever who’s spent the 2022 campaign in Double-A. A right-hander, he owns an excellent 2.27 ERA through 35 2/3 frames. Stryffeler has fanned an elite 37.7% of batters faced but walked an elevated 12.6% of opponents. The Lake Erie college product will be eligible for the Rule 5 draft this winter if he’s not added to San Francisco’s 40-man roster.

Thomas, meanwhile, was the Mariners’ fifth-round draft pick just last summer. He’s had a nice start to the season in High-A, where he’s posted a strong .264/.400/.444 with nine homers, a dozen doubles and a huge 16.2% walk rate. Thomas was a senior sign out of Baylor University, it should be noted, so he’s already 23 and is playing against notably younger competition. Time will tell how he fares against more advanced opponents, but the early results are promising. From a defensive perspective, he’s caught a roughly average 27% of attempted base thieves, but Baseball America questioned his overall receiving skills at the time of the draft.

Milone, 35, had been in his second stint with the Mariners. The journeyman southpaw has carved out a 12-year big league career, at times enjoying solid runs as a starter (2012-15, in particular) and as a reliever. The past several seasons have been a struggle for the soft-tosser, however, as evidenced by a 6.33 ERA in 69 2/3 frames. Milone was on the 15-day injured list due to a cervical sprain, but if he’s healthy in the season’s final couple months, he could latch on as a depth arm with another club.

In 944 1/3 innings at the big league level, Milone has a 4.60 ERA with a below-average 17.5% strikeout rate but an excellent 5.6% walk rate.

Robert Murray of FanSided first reported that Casali was headed to Seattle in exchange for Stryffeler (Twitter link). Jon Heyman of the New York Post reported that Boyd was going to Seattle as well.