Has the Mariners Pitching Factory done it again?
The Mariners need another leverage arm in their bullpen. Where last year the starters averaged 5.8 innings per game, this year, they’re down to 5.3. Some of that is all the starts they’ve had to give to Emerson Hancock, Logan Evans, and Luis F. Castillo, but even if/when George Kirby, Logan Gilbert, and Bryce Miller get back, the team won’t be able to rely on them for length for several weeks. And as good as the back of the bullpen is, it’s not deep. Matt Brash can’t pitch back-to-back days as he continues his Tommy John recovery. And Andrés Muñoz and Gabe Speier can’t pitch literally every day.
In past years, Seattle’s gotten away with this by manufacturing a couple pop-up guys in their Pitching Factory: Paul Sewald and Drew Steckenrider in 2021, Erik Swanson and Penn Murfee in 2022, Gabe Speier and Justin Topa in 2023. They didn’t really pull this off last year, though they largely got away with it because the rotation was so good. But they need one this year, and the position is still vacant.
I think Casey Legumina might be the man for the job.
Before we get too deep, I want to acknowledge that I’m biased in hoping for Legumina’s success because I made Legumina my Pile Pick for 2025. But still, I think there’s something brewing with the Bean Man.
The major changes the Mariners have worked on with Legumina after acquiring from Cincinnati for cash this offseason are adding a sinker and having him lean into a revamped sweeper.
Giving him a sinker is something Seattle’s pitching development is asking of basically every pitcher who can handle it. Legumina’s is pretty good, with above-average horizontal break, which is the key to a successful sinker. Here’s a vicious one running in on Austin Hays, showing Legumina’s former team what they’re missing.
He’s only thrown 27 so far, but batters don’t have a single hit off it yet, with three weak dribblers the only ones they’ve put in play compared to the four they’ve whiffed at. It’s a good pitch on its own, and by creating a contrast, it’s helping his four-seamer (which is still his bread and butter) play better than it has in years past.
The sinker is also helping set up his revamped sweeper, which he’d largely abandoned last year but is now a key weapon. Working with the Mariners, Legumina has taken some away some of the sweeper’s depth, letting its glove-side float work off the arm-side run of the sinker. You can see the difference in comparing one from 2023 to one from this year below.
The combination of changing the pitch shape and throwing it into a new mix have increased the carnage. Where he used to get swinging strikes on just 11.1% of them, now he’s getting a whiff on every five that he throws, which is in the 81st percentile for sweepers. He’s only going to it in two-strike counts about a fifth of the time, still relying much more on his four-seamer, but I’m expecting that number to rise as he gets more confident with it.
It’s a small sample, but the new and revamped pitches are working. RV/100 measures how many more runs a pitcher would prevent over the average pitcher out of every 100 thrown. His reshaped sweeper is at 3.6, which is 15th out of the 155 pitchers who’ve thrown at least 25 sweepers this year. And the new sinker has an RV/100 of 5.6, which is sixth out of 272. Even if those numbers fall as the sample size increases, that’s still a devastating pair.
The big knock on Legumina is his command. The only deep blue bar on his Savant page is his walk rate, which is knocking his K% – BB% down to 10.0%, not really the number of a leverage arm. But I’m not convinced this is a real problem.
Two of his walks came in the May 5th game against the Athletics. But let’s recall what actually happened there. Legumina came in to pitch the bottom of the 11th inning in a tie game, a crucial fact because with the ghost runner, it meant he started with the winning run at second base. When Gio Urshela started the inning by successfully getting the bunt down, suddenly the winning run was on third base with just one out. Is that really on Casey Legumina? To whatever extent it was, what happened next surely was not. Dan Wilson elected to intentionally walk Shea Langeleirs and JJ Bleday to try to set up a double play from the contact-heavy Jacob Wilson. The wisdom of that decision could be debated, but one thing that I think is beyond debate is that those intentional walks to do reflect anything about Casey Legumina’s effectiveness.
So let’s take those two batters faced out of his sample. Other guys have undeserved walks in their records too, but not everyone does, and it’s certainly not a quarter of their walks for many of them. And I’m not getting as cute about this as I could. I’m leaving in this walk to Aaron Judge, for instance, despite Ball 1 being an egregious call from the umpire, setting him up to be down 1-0 to the most dangerous hitter in the game, a guy who you’re going to be awfully careful against, and whom Legumina still came a hair’s breadth from striking out on Ball 4 anyway.
But without those two batters he “faced” in Sacramento, the Bean Man’s strikeout rate is 24.1% and his walk rate is 10.3%. It also moves that nasty sapphire bar on his Savant page to a dustier shade of blue, as he rises from the sixth percentile up to the 30th. Even doing this little exercise leaves you with more walks than you want to see. But combined with Legumina’s long-standing penchant for weak contact, it’s something you can live with.
Now to be sure, this entire article is based on just 14.2 innings. That’s how eliminating two walks has such a big impact. But when you’re trying to find a diamond in the bullpen rough early in the year, small samples are all you have, so even the data we’re working with is worth more than a hill of beans. You just have to do your best with the information that’s available to you. And I’m not trying to suggest Legumina is going to be interchangeable with Brash. But I do think that when it comes to the number four guy on the bullpen depth chart, Legumina has separated himself from the pack and earned a shot at more leverage outings.