The rotation is not what it was, but it is now who it was.
Bryce Miller returned Tuesday from a 2 1/2-month stay on the injured list. With him, the Mariners have their core rotation intact for the first time in 2025. The presumed strength of the roster is now in place as they begin their final push for the playoffs.
But expectations have already tempered. Miller in his (third) debut got smacked around by the Phillies; Logan Gilbert had the worst start of his career the night before; and George Kirby
gave up 12 hits the night before that. The rotation posted a 9.97 ERA and 6.99 FIP in their first turn of 2025.
“It sucks it took this long in the season to get us all five healthy and rolling,” Miller told the Seattle Times after Tuesday’s loss. “We just got to start stringing together good starts and giving us a chance. And I think we’ll be all right. We’re still in a good spot, and everything’s gonna be fine.”
Hurtin’
The Mariners’ rotation in 2024 was arguably the most effective in team history. Their 3.64 FIP is the org’s new all-time best. They threw more innings and walked fewer batters than any other team in MLB. Their average Game Score of 56 is among the top marks of the pitch-tracking era. Expectations were high in 2025, with all five pitchers set to return.
They simply haven’t delivered. The Mariners’ rotation ranks 14th with 8.3 fWAR through 128 games—on pace for a 30% drop from last year.
Why? Injuries, mostly. The Mariners’ top two starters each missed about one-third of the season, and Miller missed more than half the season with two trips to the IL. Injuries are to be expected for a group that logs more innings than anyone, and the Mariners’ have had reasonable injury luck in 2025. But the depth behind the core starters often struggled in their place. Emerson Hancock and Logan Evans combined for -0.4 fWAR in 30 starts, for a net loss of about 2.9 fWAR—the difference between ranking 14th and fifth.
Sense of relief
That feels like something to emphasize at the moment: when healthy, the Mariners rotation is still among the best in MLB. One bad roadtrip doesn’t represent them. They rank at the top of the league in FIP, strikeouts, walks, whiffs and all the things they were good at last year. When they’ve pitched, they’ve pitched well.
But it’s hard to shake the feeling that something is worse now. Too many starts seem to unravel too early.
That appears to be the case. The plot above shows the Mariners’ core rotation performance by times through the order. Last year, they were among the best in MLB on each turn through the order—dominating early and going deep into games. This year, they continue to dominate early, but where they often finished strong in 2024, we now see frequent collapse.
Again, the result is still quite good, even if their longevity is not what it was. They’re getting more early than they’re giving back late.
But too-short outings have compounded with a too-thin bullpen, with Dan Wilson often forced to either grit through a wobbly starter or turn the ball over to a non-competitive arm. The idea that games seem to explode in the middle innings is explicit in the data: the Mariners have the second worst team FIP in the fifth in sixth innings (5.09) and the second best team FIP in all other innings (3.74).
Diagnostics
Gilbert is the most interesting case. His “stuff” has leapt forward this year, and he’s now generating whiffs and strikeouts at an elite rate. The changes he made in the offseason (as outlined by Zach Mason in July) have worked overall. But Gilbert has a 165 sOPS+ on the third time through the order—the fourth worst split in MLB. It’s a new issue for him in 2025. Maybe he’s subtly changing his approach later in games, or maybe his “stuff” upgrade is less suited to exposure. It’s also fair to wonder whether there’s any lingering effect from his injury.
Kirby also made conscious changes ahead of 2025, now conceding some walks for more swing and miss. Early in games, he looks as good as ever, but he now has a 155 sOPS+ on the third pass—the fifth worst split in MLB. Approach? Stuff? Health?
The issues arrive even earlier for Miller, whose walk rate doubles when facing the order just the second time. We’ll see if that continues in his final attempt at 2025. The bone spurs are still there.
The only pitcher to escape this pattern is Bryan Woo, who’s gone at least six innings in each of his 24 starts. Woo’s first two seasons were marked by early exits—sometimes pre-scheduled, sometimes out of necessity. This year, he ranks top five in innings pitched and top 20 by FIP. His well-controlled and unknowable fastball is the second most effective pitch in MLB. It’s helped him get deep into games, as he can throw it relentlessly near the zone to limit walks while still generating weak contact. Woo’s progression from “good early” to “good always” is one of the most encouraging developments of 2025.
Bandage
It’s unlikely the Mariners can all of a sudden solve this issue in the final seven turns of the rotation. If they fail to win the AL West, it will likely come down to games punted in the middle innings.
Still, it’s worth considering how they stack up in October. The Mariners would likely lean on Woo, Gilbert and Kirby for all they can get. Again, regardless of longevity, they collectively represent one of the best starter trios in MLB. While Castillo and Miller no longer inspire much confidence individually, together they represent two strong passes through the order; a braided start could be the Mariners’ best bet—recreate him in the aggregate, as they say.
The plot above shows the Mariners might have another option for length. Despite pitching to replacement level overall this season, Evans has been the Mariners’ second best starter on the first time through the order. His 51 sOPS+ on the first pass is seventh in MLB and effectively tied with Paul Skenes. Maybe he won’t always be so dominant, but something about his kitchen-sink approach seems to stump batters for a bit. He could be a useful bridge in the middle innings, assuming his placement on the injured list is not the end for 2025.
That’s what it’s come to for the Mariners’ vaunted rotation. Fantasies about playoff potential now require a bit of administrative wrangling. The group still looks better than most as they begin their first and final turn.