Logan Gilbert’s Injury Means Another Patch for the Mariners Rotation

Particularly in light of their failure to upgrade their roster this winter, starting pitching is the foundation of the Seattle Mariners. Last year, four of their starters took at least 30 turns, and the unit posted the majors’ lowest ERA (3.38) while ranking either first or second in the American League in FIP and WAR as well. But while this year’s Mariners are currently running first in the AL West at 17-12, their rotation has scuffled, in part because it’s far from whole. George Kirby, who led the staff in WAR last year, began the season on the injured list due to shoulder inflammation, and now Logan Gilbert, who made the All-Star team and received Cy Young votes, has joined him there due to a flexor strain.

The 27-year-old Gilbert made his sixth start of the season on Friday night at T-Mobile Park against the Marlins. While the results were impressive — he needed just 29 pitches to throw three perfect innings, striking out three — his average four-seam fastball velocity was down 1.1 mph from his season average of 95.6, and his slider and curve were a bit slower than usual as well. He did not return for the fourth inning, replaced by reliever Casey Lawrence, and the Mariners soon announced that he had departed due to forearm tightness.

“I felt it a little bit warming up,” said Gilbert. “Just never really went away. Sometimes you just get going and it feels a little better. Tonight, it just didn’t.”

As MLB.com’s Daniel Kramer described it, both Gilbert’s pregame long-toss and warm-up pitches were of lesser intensity — he mostly didn’t use a windup for the latter — than usual. He didn’t throw a single split-fingered fastball because of the stress the pitch places on his forearm. “We didn’t think it was a good idea,” he said, as though throwing mid-90s fastballs and breaking balls through discomfort was otherwise perfectly sound logic.

At the very least, powering through seems to have been a product of Gilbert’s workhorse mentality. He’s been one of the game’s most durable starters in recent years, with 103 starts since the start of the 2022 season, tied with Aaron Nola for fourth in the majors, behind Logan Webb (105), Dylan Cease and Miles Mikolas (both 104). His 208.2 innings led the majors last year, and his 615.1 innings over the aforementioned span ranks fourth behind Webb, Nola, and Corbin Burnes. “I take a lot of pride in that, just kind of how I want to be known — eating innings and being dependable and being healthy,” said Gilbert. “I can’t control all of that. But I’ve been healthy and never really came out of a start. I think this is the first one.”

An MRI taken on Saturday revealed that Gilbert had suffered a Grade 1 flexor strain, meaning that it was a mild one, “relatively good news,” as the righty said. He was placed on the 15-day injured list for the first time in his career, and will be shut down from throwing for at least two weeks before being reexamined. A return sometime in June is the best-case scenario.

The injury interrupts a promising start to Gilbert’s season. His 37.6% strikeout rate and 32.5% strikeout-to-walk differential both lead all qualifiers in either league, while his 2.16 FIP ranks second in the AL, his 1.0 WAR is tied for fifth, and his 2.37 ERA places eighth. He’s been especially effective at avoiding opposing hitters’ barrels; his 4.5% barrel rate is the second-lowest among AL qualifiers behind only teammate Bryce Miller (3.8%).

Gilbert finished sixth in the AL Cy Young race last year on the strength of a 3.23 ERA, 3.27 FIP and 4.1 WAR, and tied for second in the voting in our preseason staff poll. One notable change in his approach from 2024 to ’25 is that he had been throwing his splitter more often: 21.2% (22.6% prior to Friday), up from 13.4%. The pitch has been especially effective; last year, batters hit .101 and slugged .162 while whiffing on 50.6% of their swings at the offering, while this year, they’re at .067 AVG (1-for-30) and .100 SLG with a 50% whiff rate. In light of Gilbert’s words and approach on Friday, it’s fair to wonder whether that uptick in usage factored into his injury, and whether he’ll back off his increased reliance on the pitch once he returns.

To replace Gilbert, the Mariners recalled 23-year-old righty Logan Evans — not many teams can pull off a Conservation of Logans — from Triple-A Tacoma. A 2023 12th-round draft pick out of the University of Pittsburgh, the 6-foot-4, 215-pound Evans pitched to a 3.20 ERA and 3.83 FIP with a 21.9% strikeout rate at Double-A Arkansas last year, his first full-season assignment. Per Eric Longenhagen, he’s improved his outlook from last summer by leaning more heavily on his 70-grade slider (it’s a sweeper). Notes from Longenhagen:

Evans has begun to take a sweeper-first approach to pitching. Whereas last year he was using it 31% of the time, so far this year his breaking ball usage has been 46%. It makes sense, as it’s easily his best pitch. Evans’ slider spins at 2,800 rpm and has hellacious lateral wipe. His reliance on it robs it of some bat-missing ability, and Evans’ slider’s miss rate the last couple of years has been pretty average because he’s so often trying to throw it for strikes and hitters anticipate its arrival. But because Evans’ fastball is fairly vulnerable, he’s forced to lean on his breaking stuff. His low-to-mid-90s sinker (sitting 93-94, up to 97) has only generated six whiffs across 200 total pitches so far in 2025 (including his big league start), and as of this writing, hitters (in the minors and majors combined) have a .965 OPS against his mix of sinkers and four-seamers.

Evans can change pitch shape and speed off of his primary sinker/sweeper mix. He’ll throw some harder cutters around 87 mph, as well as some slower curveballs and changeups, mostly to lefties. Again, it’s really only the slider that’s plus, but Evans has a super deep repertoire, he throws a good rate of strikes and gets groundballs, and in 2024, he proved he could sustain this kind of stuff across more than 100 innings. Without a single pitch generating plus miss, he’s probably not going to be a star, but he does enough to be a useful member of a big league rotation, and his 45 FV grade is above the 40+ FV of last cycle when I thought Evans looked more like a nasty swingman or long reliever.

Evans made his major league debut on Sunday against the Marlins, allowing two runs on two hits and three walks while striking out three in five innings; he got his first W in Seattle’s 7-6 victory. Both his four-seamer and sinker sat in the 91-95 range and averaged 92.9 mph, matching his marks at Tacoma. He threw six different pitch types including the two fastballs, a cutter, a sweeper, a curve and a change, but generated just four whiffs and a 17% CSW rate from among his 78 pitches.

The plan is for Evans to continue filling Gilbert’s slot, at least until Kirby returns, which will likely be sooner than Gilbert. The 27-year-old, who pitched to a 3.53 ERA and 3.26 FIP in 191 innings last year, was shut down on March 7 due to shoulder inflammation. He received a biologics injection — a nonspecific term that could include platelet-rich plasma and stem cells — to speed the healing process, and has progressed in his throwing program to the point that he threw a bullpen session in Seattle on Friday and a live batting practice session on Monday. Per the Seattle Times’ Adam Jude, he threw 35-40 pitches to a pair of hitters from High-A Everett and “felt awesome.” He could begin a rehab stint as soon as this weekend, either with Tacoma or Everett due to their proximity to Seattle, and will build up his pitch count to the point where he can handle five innings, or around 80 pitches. In other words, he’s probably about a month away.

Kirby’s spot in the rotation is currently being filled by Emerson Hancock, who was lit for six runs in two-thirds of an inning in his first start on March 31, then optioned to Tacoma. The 25-year-old righty, who scuffled in his 12-start stint with the Mariners last year (4.75 ERA, 5.69 FIP), has done much better since returning, allowing four runs in 11 innings while striking out 11 in starts in Cincinnati and Boston, two tough places to pitch.

During Hancock’s brief exile to Tacoma, his spot in the rotation was filled by Luis F. Castillo, which isn’t what you call this guy when he makes a great start or pitches his way out of a jam with an emphatic strikeout. The Castillo in question is a 30-year-old righty who spent 11 seasons beating the bushes before making three appearances for the Tigers in 2022, and then took a two-season detour to Japan, where he pitched for the Chiba Lotte Marines and the Orix Buffaloes. In his two turns for the Mariners, he totaled seven innings, seven runs allowed (six earned) and seven walks. Yikes.

As for “the real” Castillo — who early in his career had to escape the shadow of his namesake second baseman — he’s pitched to a 3.63 ERA and 3.93 FIP in a staff-high 32.1 innings thus far. His performance contains all kinds of warning signs, starting with an average four-seam velocity that’s dipped to 94.8 mph, from 95.6 in 2024 (and 96.3 in ’23, and 97.1 in ’22); by both Stuff+ and PitchingBot, the quality of his stuff is down. His strikeout rate has plummeted to 19.7% and his walk rate has risen to 9.9%; his 9.9% strikeout-to-walk differential is less than half what it was two years ago (20.3%). What’s more, when batters have made contact, they’ve hit him for a 90.3 mph average exit velocity, 11.1% barrel rate, and 44.4% hard-hit rate, all of which are career worsts.

For his part, Miller threw five scoreless innings in a 5-3 win over the Angels on Tuesday night, working around five walks and two hits. His walk rate is now an astronomical 14.7%, tops among all qualified starters, and his strikeout-to-walk differential has shrunk from last year’s 17.9% to 9.3%. Batters haven’t been chasing either his splitter or his slider to the extent they did last year, and so neither pitch has been as effective. He’s offset that by avoiding barrels, but his 90.1 mph average exit velo and 43% hard-hit rate suggest he’s walking a tightrope.

Bryan Woo has been the team’s best starter this side of Gilbert, posting a 3.09 ERA and 3.16 FIP. He’s gained nearly a full tick on his four-seamer (95.7 mph, up from 94.8), and the pitch has become one off the majors’ most effective thanks in part to the deception created by his low arm slot (27 degrees). Batters have hit just .154 and slugged .288 against it thus far while whiffing on 32.5% of their swings (10th among pitchers with at least 100 four-seamers thrown). His walk rate has just about doubled over his 2024 rate as well, though the jump from an otherworldly 2.8% to a still-impressive 5.5% isn’t a big deal, particularly when it’s offset by improved strikeout and home run rates.

Maintaining a rotation as durable as that of the Mariners has become a very tall task. Over the past decade, just one team has had the same four starters make 30 starts in back-to-back seasons, the 2015–16 Cubs (Jake Arrieta, Jason Hammel, Kyle Hendricks and Jon Lester). The Mariners won’t be the second, and won’t even join the short list of teams in that span with a trio of starters repeating with 30 starts. Besides Castillo, Gilbert, and Kirby doing so in 2023–24, the only company they have is the Blue Jays of the same seasons (Chris Bassitt, José Berríos, and Kevin Gausman), and the 2016–17 Nationals (Gio González, Tanner Roark, and Max Scherzer).

All told, the Mariners rotation ranks just 12th in the majors in ERA (3.74) after last year’s major league best 3.36 mark. They’re a more impressive fourth in FIP (3.42); they were third last year, but with a 3.64 mark. Their bullpen, which owns a 3.79 ERA and 4.24 FIP, hasn’t been much to write home about either save for Andrés Muñoz and Gabe Speier. Muñoz is 11-for-11 in saves and has thrown 15 scoreless innings with 19 strikeouts and just 11 baserunners. Speier, the top setup man, had allowed just one run in his first 11.2 innings but was charged with two while getting only one out on Tuesday; he now has an ERA and FIP of 2.25 ERA. The next guys down on the leverage chain — Gregory Santos, Carlos Vargas, Trent Thornton and Eduard Bazardo — have been much less effective. Santos is now on the 60-day injured list following a surgical cleanup of his right knee, but Matt Brash is on his way back from Tommy John surgery, having begun his rehab stint on April 14.

Perhaps the real story out of Seattle, or at least one that deserves a deeper dive than I can cover here, is the Mariners’ offense. The team is scoring 4.93 runs per game, third in the AL and about three-quarters of a run ahead of last year. They’re second in the majors with a 125 wRC+, and are actually carrying a 125 wRC+ since August 22 of last year, when Hall of Famer Edgar Martinez (yeah, I still get goosebumps when I type that) replaced Jared DeHart as hitting coach, part of the staff shakeup that included Dan Wilson taking over for Scott Servais as manager. Julio Rodríguez (104 wRC+) is off to another slow start, but Jorge Polanco is hitting a bonkers .389/.423/.819 (258 wRC+) while being limited to hitting from the left side due to an oblique strain (see Davy Andrews here), with Dylan Moore (163 wRC+, but currently on the 10-day IL due to right hip inflammation), Cal Raleigh (160 wRC+), J.P. Crawford (145 wRC+), and Randy Arozarena (124 wRC+) all doing excellent work as well.

We can probably expect that offense to regress somewhat, if not all the way to the dire state of the pre-shuffle squad. So long as Gilbert and Kirby are able to return as planned, this team has a solid chance at a division title (44.6%, per our Playoff Odds) or at least a Wild Card berth (29.1%), but we’ll see if that plan and those performances hold up.

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