Charting Vibes: The 2025 Mariners Starting Rotation

The Gang Writes a Positive One

It’s a rare back-to-back post week here at The Light Bat. If you missed yesterday’s vital breakdown of the Mariners announcing a Nintendo patch on their uniform, please consider getting current before reading on.

With Opening Day less than a week away, today we’re wrapping up our positional Vibe Compass breakdown. The outfield edition was mostly what you want i.e. good dudes rockin’, whereas the infield was decidedly tilted towards dorks and/or hubris punishment. The bullpen will get a separate Vibe Compass next week but it will not be the same as these, because bullpens are fake and pretending to understand or predict them is fickle alchemy. Today, we’re tackling the crown jewel of the Seattle Mariners: The starting rotation.

Let’s not quibble with this thing: This is the greatest collection of starting pitching talent in franchise history. Over the next six months we will learn where this particular season ranks in team annals but, at least as it concerns the nearly half a century of Mariners baseball the group of Logan Gilbert/George Kirby/Luis Castillo/Bryce Miller/Bryan Woo already stand alone.

It is a group defined not so much by individual brilliance, historical milestones, or awe-inspiring pure stuff as it is its otherworldly, unceasing depth. For practically any other baseball team the back end of the rotation features arms in various stages of disrepair, development, or decline. The Mariners, by contrast, feel almost more exciting the further down the rotation you go. I will discuss at length each of these dudes in a bit, but suffice to say no major league team outside of Seattle’s offers the opportunity to melt faces with arms like Bryce Miller and Bryan Woo in the four and five spots. The lack of any real break in arm quality and consistency is the Mariner’s best weapon, and gives them a massive pitching advantage in 60%+ of their games.

Yet, while a fleet of shiny and shockingly maintenance-free sports cars is a luxury unique to the Mariners in 2025, it’s fair to question whether any one of them individually can hang with the sport’s true supercars. A 911 is a miracle of a thing, and owning five of them qualifies you as a Certified Opulent Pitching Oligarch. Still, none of them is beating a Bugatti off the line.

There are other quibbles as well. No one would ever call this group fraudulent, but it is fair to question how much of their excellence is driven by playing their home games on Saturn AKA T-Mobile Park. Durability, the unfailing calling card of this group for the past two seasons, is already in question with George Kirby starting the season on the IL with “shoulder soreness”. They are the idol of the most annoying current baseball fan group - extremely online and willing to browbeat you with a million graphs, charts, and metrics involving break, arm slot, and spin rate in order to get you to admit what is already clear and obvious to the naked eye:

These guys pitch real good, man.

Quibbles aside they are the honey in this pot, the juice in this melon, the gas in this tank. They make everything else in this organization work, despite very little of it being particularly good. Let’s take a look at them individually, starting with the Opening Day starter.

Logan Gilbert

All Mariner starting pitchers until the end of time will be judged by how much watching them reminds me of Felix Hernandez. Does this mean occasionally I find deep pleasure in watching the Mariners hang a starter out to dry as he goes something like 8.1 innings, allowing one run (on a fielder’s choice) as the Mariners scuffle against Jeffinald Midman in a 2-0 loss? Was Tommy LaStella an odd choice for 2023 Opening Day DH?

Anyway, of all the current guys, Logan reminds me the most of Felix. He has the most diverse pitch mix, is underratedly cerebral, was the only 2024 Mariners starter to go more than eight innings in a start (he did it four times), led MLB in innings pitched in 2024, had a hilariously non-representative win-loss record (9-12), and he’s an absolute maniac who would cut off a toe if it meant he could face one more batter.

The expectations for Gilbert’s career were something like a mid-rotation fixture, and that has proven to be his floor. He has improved every season of his career and heads into 2025 as both the clear ace of this excellent staff, and a top 10 pitcher in MLB. If the Mariners can win the (absurdly winnable) AL West there’s no reason Gilbert can’t be in the Top 3 of Cy Young voting, with a decent chance of winning it.

Pitchers are fickle and unpredictable by nature, even within the fickle and unpredictable confines of a sport whose beating heart is “Sphere Moving At Lightning Speed Struck By Haphazardly Wielded Cylindrical Staff”, but Logan feels like a safe bet to once again be an excellent starting pitcher in 2025. This dude? He rocks.

Luis Castillo

The crowning member of an intensely curious - albeit small - segment of Jerry Dipoto Mariner moves that can only be summarized as “Extremely cool moves that worked perfectly that the team still seems vaguely dissatisfied with”. I already wrote earlier this offseason about Luis, and what an excellent pitcher he has been since coming to Seattle. The short version is over the past three seasons he’s something like one of the 10 best pitchers in the sport.

And yet, ever since the 2023 season ended there has felt like a slowly growing discontent with him among the Mariner upper levels. He was subject to trade rumors for a large part of the winter, before the team rightly decided the return available simply made no sense. Still, the team’s ownership/management seems to have issue with any player whose performance can be categorized as anything but an incredible “value” for the organization, and Luis being fairly compensated while slightly declining from his career norms in both results and stuff metrics is not how you end up starring in Moneyball 2.

Now I will acknowledge it’s fair to wonder how close to the end Luis is, given that he appears to have started his career’s loss-of-altitude era. It would be great to see him give up fewer home runs and work deeper into games in 2025. We’ve seen pitchers fall off the cliff here before, and career ending/altering injuries are always only one pitch away.

That said if I had to guess Castillo will continue to be a certifiably good pitcher in 2025. It is worth noting if he is healthy and moderately productive his no-trade clause expires next offseason. Given that I think there’s a very good chance this is the last year of Castillo wearing a Mariners uniform.

If that is to be so I hope history doesn’t twist it. Acquiring Luis Castillo was an awesome move and it immediately paid off with some of the greatest postseason pitching in franchise history. If he feels like an afterthought in this rotation to you, think again, and think better. This dude? Also rocks.

George Kirby

At his best, easily the most aesthetically-pleasing pitcher in the rotation to watch. Good George is the ur-modern pitcher; a gleaming, towering testament to the glory of economy and efficiency. Watching him is witnessing the act of pitching distilled to its barest, purest necessities. The windup has no flair, no distinct quirk. It is not rushed nor theatrically lackadaisical. His stuff is excellent but not in a way designed to have you notice. If he could, he would happily get every single hitter out on a first pitch groundball to second, as that would get him to bed early enough to wake up for prime bird-watching hours.

I’ve already mentioned that Felix Hernandez is my ideal pitcher-watching experience, and since Felix no one has put together such a stirring homage to The King as George did on August 12th, 2023 by throwing nine innings of the most obscenely ruthless pitching I’ve ever seen in a brutal, beautiful, iconic 1-0 Mariners loss. Felix was there to see it in person. It ruled.

George was a bit more up-and-down in 2024 than you’d like, largely due to some struggles with lefties that a new cutter is reportedly designed to combat. As mentioned previously, he’s also starting the season on the IL with shoulder soreness. I’m going to assume everything is going to be ok there because I love watching George pitch and him being hurt would make me sad.

For various reasons (injury concerns, cost, continued inability to locate Seattle on a map, etc.) I think he’s probably the least likely of the current guys to sign an extension with the team, which means our time with George could be fairly limited. At his best he’s the best they’ve got, so I intend to enjoy anytime he steps on the hill. This dude? He rocks (politely).

Bryan Woo

Almost certainly the crown jewel of the Mariners’ pitching development pipeline, Woo threw fewer than 80 innings in college, and started only 10 games. The Mariners drafted him in the 6th round in 2021, tinkered with his pitch mix, kept him healthy despite a ragged injury history, convinced him he was good, and then unleashed him on the league.

Watching Woo pitch is watching a world class beam routine: Exhilarating athleticism, immense danger, and impossible precision combined with far too much dead time to think and worry. I confess I have spent every Bryan Woo start to this point horrifically concerned that something bad is going to happen, which makes the beautiful, artistic way he carves through hitters really stand out in my mind. He throws that fastball on the outer edge and it looks so, so hittable but it just gets a half-inch or so above the barrel every time. Hitters leave at-bats against Woo with the same feeling I do as an observer: I can’t believe he missed that.

But, they do! Woo’s starts are for me a thrilling mixture of fear, anxiety, and admiration for just how good he actually is. It makes no sense that the Mariners just plucked this guy out of UC San Luis Obisbo, fed him into their matrix, and 3D printed a top-shelf mid-rotation Kroger-brand Roy Oswalt. But, they did! This dude? Rocks! Somehow!

Emerson Hancock

The pair of sweats deep in your drawer you put on after your cat pukes on your favorite pair while sitting on your lap. The have two legs but the elastic is stretched, and the pocket is too small for your wallet. It will work for a few days but if the vomit stain won’t come out on those nice sweats you’re gonna have to get a new pair.

Needs to get his fastball up to the velo his football program’s players drive to Zaxbys. Go dawgs. This dude? I am open to him starting to rock but at present he does not.

Bryce Miller

Two facts here:

1) Pitchers are not cool

2) Bryce Miller is, by a significant amount, the coolest 2025 Seattle Mariner

While always acknowledging that the Milkshake Duck lies around every twist and turn of professional athlete fandom, there is nothing about Bryce Miller’s known public persona I find less than delightful. He seems exceptionally self-aware and comfortable with the fact that he’s a living country western stereotype to all of us Northwest city slickers, and has shown zero compunction on changing that impression.

This is, then, the platonically ideal fan/player relationship. Bryce seems perfectly content for me to believe his highest aspiration is being allowed to take the mound in a 10-gallon Stetson with a Lone Star strapped to his hip, and I’m perfectly happy in letting that be the limit of all I know about him.

He’s a pitcher from Texas, yes, but more importantly he’s The Pitcher From Texas(™). I don’t need my baseball players to exist too much on the z-axis, unless (and sometimes specifically because) they really want me to. Bryce seems to come to all this quite naturally, like a coyote howling at the moon or some such, and I’m grateful for it. Until otherwise noted he is the rotation’s Mayor of Chillsville; its King of Cold Ones.

As for pitching? Well he’s a gosh darned delight is what he is. Of all the Mariners’ starters nobody throws a pitch more perfectly spiritually-aligned than Bryce Miller’s fastball, which hums with the country joy of a leisurely-plucked banjo as it sears directly past and/or through your baseball bat. Logan Gilbert is the best pitcher the Mariners have, and George Kirby’s alien efficiency is their most jaw-dropping quality, but no one on this team infuses the joy of self into their craft like Bryce Miller. His every movement is living testament to His Whole Deal, from the bow-legged saunter off the mound to the foal-like skip after releasing a slider.

The coolest Seattle Mariner of them all, and one of the very best. This dude? Nobody rocks harder.