White Sox's Luis Castillo: Stumbles in White Sox debut
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Castillo allowed five runs on six hits and a walk over four innings in a no-decision Thursday against the Red Sox. He struck out five.
After holding Boston hitless through his first two innings, Castillo gave up a two-run homer to Connor Wong in the third before surrendering three runs in the fourth to tie the game at 5-5. It's certainly wasn't the ideal White Sox debut for Castillo, who struggled to a 6.35 ERA across 17 innings in his final three starts with the Mariners before being shipped east at the trade deadline. Through 103.2 innings this year, his ERA sits at 5.30 -- he hasn't finished a season with an ERA above 4.00 since 2018, his first full year in the majors. Castillo will look to turn things around his next time out, tentatively lined up to come at home against the Reds, the team he began his career with in 2017.
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White Sox's Luis Castillo: Moving on to White Sox
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The White Sox acquired Castillo from the Mariners on Saturday in exchange for right-hander Seranthony Dominguez, outfielder Nolan Jones and catcher Boston Smith, Jeff Passan of ESPN.com reports.
The 31-year-old righty will head to Chicago and bolster a rotation that's received excellent results from Davis Martin and Sean Burke but uneven production from Anthony Kay, Noah Schultz and Erick Fedde at the other three spots. While the three-time All-Star easily becomes the White Sox's most battle-tested starter, Castillo has endured a career-worst 2026 campaign. After submitting a 3.54 ERA and 1.18 WHIP in 32 starts for Seattle a season ago, Castillo turned in a 5.06 ERA and 1.39 WHIP in 20 appearances (17 starts) in 2026 prior to being dealt. Castillo showed signs of righting the ship in May and June, but he went 0-3 with a 5.48 ERA and 1.52 WHIP while serving up seven home runs in 23 innings over four July outings. He last pitched Tuesday, so Castillo could be ready to make his White Sox debut during the team's series in Boston early next week.
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Mariners' Luis Castillo: Gives up five runs against Dodgers
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Castillo allowed five runs on 11 hits and two walks while striking out two over five innings in a no-decision versus the Dodgers on Tuesday.
Castillo gave up multiple home runs for the third start in a row, as Shohei Ohtani led off the bottom of the first inning with a long ball and Max Muncy went yard in the fifth. This was the first time Castillo had allowed five earned runs since April. July was a rough month for the veteran, who gave up 14 runs over 23 innings across his four outings. On the year, he has a 5.06 ERA, 1.39 WHIP and 86:32 K:BB across 99.2 innings over 20 games (17 starts). Castillo is tentatively projected to make his next start at home versus the Tigers, but that is a loose projection given the likelihood the Mariners move a pitcher before the trade deadline.
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Mariners' Luis Castillo: Works seven innings in loss
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Castillo (3-9) allowed three runs on four hits and two walks while striking out three over seven innings to take the loss Tuesday versus the Reds.
Two of the four hits Castillo allowed were solo home runs, though it was Sal Stewart's sacrifice fly in the fifth inning that ultimately sealed the loss for Seattle. This was a third straight defeat for Castillo, who has allowed nine runs over 18 innings with an 11:4 K:BB in that span. For the season, he has a 4.85 ERA, 1.33 WHIP and 84:30 K:BB through 94.2 innings across 19 appearances (16 starts). Castillo is tentatively lined up for a tough road start versus the Dodgers next week, though he is a candidate to be traded if the Mariners want to clear their logjam of starters.
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Mariners' Luis Castillo: Earns quality start in loss
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Castillo (3-7) allowed two runs on five hits and a walk while striking out four over six innings to take the loss versus the Blue Jays on Friday.
Castillo was mostly fine, but he allowed both runs and four of the five hits on his line during the third inning. The Mariners mustered just six baserunners in the game, giving Castillo virtually no support. He has posted back-to-back quality starts but still has just one win in his last five outings. Castillo is at a 4.79 ERA, 1.33 WHIP and 77:27 K:BB through 82.2 innings over 17 games (14 starts) this season. The veteran right-hander is tentatively projected for a road start in Miami next week.
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Mariners' Luis Castillo: Quality start in win
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Castillo (3-6) earned the win against the Guardians on Friday, giving up one earned run on four hits and a walk while striking out four batters across six innings.
A first-inning RBI double from Kahlil Watson gave the Guardians an early 1-0 lead, but that ended up being the only run Cleveland would score against Castillo, who allowed just three additional baserunners before departing the game after six innings. Friday marked the 33-year-old's first win since the end of May, as well as his first quality start since his season debut March 30. He'll take a 4.93 ERA and 1.36 WHIP into his next start against the Angels, who have turned in a .758 OPS since the beginning of June.
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Mariners' Luis Castillo: Part of pitching tandem Friday
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Mariners general manager Justin Hollander said Tuesday that Castillo will work in relief behind starter Bryce Miller during Friday's game against the Red Sox as part of a piggyback arrangement, Adam Jude of The Seattle Times reports.
Castillo and Miller made standalone starts in both of their last two appearances, but the two will shift back into a tandem setup Friday. They previously worked in a piggyback arrangement on three occasions back in May, with Miller covering between five and 5.2 frames in those games and Castillo ranging between 2.1 and five innings. According to Hollander, the Mariners plan to condense their rotation to five through the All-Star break, with all six of their starters rotating through and being part of at least one piggyback game over the next month. Hollander noted that it was merely a coincidence that the new staff-wide piggyback plan is beginning with Miller and Castillo, so both are expected to be separated and make traditional starts when their turn in the pitching schedule comes up again next week.
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Mariners' Luis Castillo: Receiving start Sunday
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Castillo is slated to start Sunday's game against the Tigers, Adam Jude of The Seattle Times reports.
Castillo and Bryce Miller worked in tandem in each of the previous three turns through the rotation, but both pitchers will receive standalone starts during the final two games of the series in Detroit. Though he currently maintains an ugly 5.53 ERA and 1.45 WHIP on the season, Castillo took some steps forward over his last two outings, covering nine innings between a start and relief appearance behind Miller while striking out nine batters and yielding two runs (one earned) on four hits and four walks. Mariners manager Dan Wilson hasn't outlined his plans for the rotation beyond this weekend, so Castillo could need another positive showing in Detroit to avoid falling back into a piggyback arrangement with Miller or shifting into a full-time bullpen role.
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Mariners' Luis Castillo: Snags extra-inning win
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Castillo (2-5) allowed two runs (one earned) on two hits and two walks with three strikeouts over five innings of relief, earning the win despite taking a blown save Sunday versus the Diamondbacks.
Castillo couldn't hold the 1-0 lead in the sixth inning after Bryce Miller's five frames of one-hit ball. This was still a positive showing for Castillo, who has given up just four runs (three earned) over 11.1 innings while adding a 13:6 K:BB over his last three appearances. He has a 5.53 ERA, 1.45 WHIP and 56:22 K:BB across 55.1 innings through 12 outings (10 starts) this year. The Mariners' fifth spot in the rotation is set to come up again on the road versus the Tigers -- if the team continues to deploy a tandem, Castillo and Miller would likely share another game despite the pitchers' discomfort with the ongoing arrangement.
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Mariners' Luis Castillo: Working behind Miller on Sunday
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Castillo is slated to work out of the bullpen and will piggyback starter Bryce Miller during Sunday's game against the Diamondbacks in Seattle, Adam Jude of The Seattle Times reports.
Though both Castillo and Miller have expressed a reluctance to being used in a piggyback arrangement, the two pitchers will nonetheless operate in a tandem for a third consecutive turn through the rotation. The setup worked well the last time out Monday in Sacramento, with Castillo starting the game and delivering one of his better efforts of the season, as he struck out six and allowed just two hits and two walks over four scoreless frames. Miller followed with five innings of two-run ball and was credited with the win, but Castillo should have better odds of factoring into the decision Sunday while he and Miller are used in the opposite order. The Mariners will reassess their rotation plans after Sunday's contest, and Castillo may need another strong showing against Arizona to ensure that he avoids moving into a full-time relief role.
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Mariners' Luis Castillo: Excellent as opener
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Castillo allowed two hits and issued two walks while striking out six batters over four scoreless innings in a no-decision against the Athletics on Monday.
After struggling mightily as a traditional starter this season, Castillo was deployed out of the bullpen for the first time in his career in his previous appearance May 19. The veteran righty was then moved back into a starting role Monday, but the plan all along was to pair him with Bryce Miller. Castillo ended up thriving with that setup, holding the A's to just two hits while racking up 12 whiffs and six punchouts over four frames. He was pulled after 68 pitches in favor of Miller, who fared well himself in closing out the contest by giving up two runs over five innings. It remains to be seen how Seattle will use Castillo going forward, but he made a case to remain a starter -- at least as part of a tandem -- with his performance Monday. Of course, it will dampen his fantasy value considerably if he's limited to fewer than five innings and 70 pitches as he was against the A's.
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Mariners' Luis Castillo: Piggybacking Miller on Tuesday
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Castillo is slated to piggyback starting pitcher Bryce Miller during Tuesday's game against the White Sox, Adam Jude of The Seattle Times reports.
Castillo will be making the first relief appearance of his MLB career Tuesday after going 1-4 with a 6.34 ERA and 1.57 WHIP through his first nine starts of the season. Since Miller covered 5.1 innings in his 2026 Mariners debut last week in Houston following his return from the injured list, manager Dan Wilson is likely to let Miller work as long as he's effective against the White Sox. With that in mind, Castillo's innings projection for Tuesday is highly variable, and how he and Miller both perform could determine how Seattle sets up its rotation moving forward. If Miller comes through with a strong outing Tuesday, he'll likely draw another start the next time the fifth spot in the rotation comes up, while Castillo could be thrust into a more flexible bullpen role on a longer-term basis.
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Mariners' Luis Castillo: Tagged with another loss
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Castillo (0-4) was tagged with the loss Saturday against the White Sox, allowing four runs on five hits across four frames. He struck out six.
This loss against Chicago ballooned Castillo's woeful ERA to 6.57 across 38.1 innings in eight outings this year. He's lost his past three starts and has given up at least four runs in each of those games. Castillo has been confirmed to start Thursday against the Astros, but according to Ryan Divish of The Seattle Times, after that the Mariners plan to piggyback him with Bryce Miller in the rematch series against the White Sox that runs May 18-20.
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Mariners' Luis Castillo: Fans six in no-decision
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Castillo tossed five innings against the Athletics on Tuesday, allowing two runs on five hits and two walks while striking out six batters.
Castillo gave up a run in the first inning and another in the fourth but kept Seattle in the contest throughout his time in the game. The right-hander wasn't very efficient, however, as he needed 95 pitches to complete five frames. That was partly because he had his swing-and-miss stuff working -- Castillo recorded 14 whiffs, and his six punchouts were his second most through five starts so far this season. The veteran hurler is still looking for his first victory, which he'll try to notch in what's projected to be a matchup versus Minnesota on the road his next time out.
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Mariners' Luis Castillo: Ineffective again Sunday
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Castillo allowed seven runs on 10 hits and one walk while striking out three batters over 3.1 innings in a no-decision against Houston on Saturday.
The Mariners gave Castillo a two-run lead in the first inning, but the veteran hurler fell behind when Taylor Trammell cleared the bases with a three-run double in the second. Castillo gave up three more runs in the third and another in the fourth before being pulled with one out in the latter frame. After tossing six scoreless innings against the Yankees in his first start of the campaign, Castillo has surrendered 11 runs (10 earned) over seven frames across his past two outings. He'll try to get back on track in his next start, which lines up to be a road outing in San Diego.
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Mariners' Luis Castillo: Strong finish to spring slate
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Castillo allowed one run on four hits and a walk while striking out five across five innings in Monday's matchup with the Padres.
Castillo finished Cactus League play on a high note, allowing three runs over nine innings in his final two outings. It's certainly an encouraging development after the right-hander struggled to a 27.00 ERA in his first three appearances (six innings). Castillo, who's posted a sub-4.00 ERA in each of his last seven seasons, made a team-high 32 regular-season starts in 2025, finishing with a 3.54 ERA, 1.18 WHIP and 162:46 K:BB across 180.2 innings.
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Mariners' Luis Castillo: Bounces back in ninth win
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Castillo (9-8) earned the win over Atlanta on Sunday, allowing one run on four hits and no walks across six innings. He struck out six.
It was a much-needed outing for Castillo, who earned his first win since July 28 -- he'd struggled to a 10.06 ERA in his previous four starts (17 innings). Overall, Castillo's ERA sits at 3.85 on the year with a 1.27 WHIP and 144:44 K:BB through 29 starts (161.1 innings). Castillo will look to build on Saturday's effort his next time out, currently lined up for next week against the Angels.
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Mariners' Luis Castillo: Skid continues Monday
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Castillo (8-8) allowed five runs on six hits and a walk while striking out five over four innings to take the loss versus the Rays on Monday.
Castillo was held under the five-inning mark for the third time in his last four starts. In that span, he's surrendered 19 runs over 17 innings, including six home runs, one of which came off the bat of Nick Fortes in the second inning of Monday's contest. Castillo is also winless in his last six outings, though he's taken just two losses in that span. For the season, he's now at a 3.94 ERA, 1.29 WHIP and 138:44 K:BB through 155.1 innings over 28 starts. He'll look to get back on track over the weekend in a road start at Atlanta.
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Mariners' Luis Castillo: Ambushed early in no-decision
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Castillo did not factor into the decision Tuesday, allowing five runs on five hits and three walks over five innings in a 7-6 loss against San Diego. He struck out six.
Castillo ran into immediate trouble Tuesday, surrendering all five of his earned runs in the first inning, punctuated by a Ramon Laureano grand slam. The 32-year-old hurler has hit a rough patch, pitching to a 5.45 ERA and 1.51 WHIP over 36.1 innings in his past seven starts. He's lined up to next take the mound Monday at Tampa Bay.
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Mariners' Luis Castillo: Settles for no-decision Friday
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Castillo didn't factor into the decision in Friday's 3-2 win over the Rays, giving up two runs on five hits over seven innings. He struck out five without walking a batter.
All the damage off the veteran righty came on solo shots by Brandon Lowe in the first inning and Junior Caminero in the sixth, but all of Seattle's offense came on a three-run blast by Cal Raleigh in the eighth. Castillo delivered his 14th quality start of the year on 99 pitches (72 strikes), and he's allowed three earned runs or fewer in eight straight trips to the mound, posting a 2.25 ERA, 1.02 WHIP and 45:7 K:BB through 48 innings over that span. He'll look to get back in the win column in his next outing, which is scheduled to come on the road next weekend against the Mets.
