40 in 40: Gabe Speier is not a good lefty reliever

Is Gabe Speier a lefty? Yes. Is he a reliever? Yes. Is he good? Yes. And yet, to describe him as a good lefty reliever is a disservice. There’s something about describing someone as a lefty reliever that feels caveated. It always reads as implying that a pitcher is only good “for a lefty” or that he’s a special-use weapon who can be called upon to get lefties but needs to be pulled before he loses his natural advantage.

What I mean is perhaps best demonstrated through a couple counterexamples: Josh Hader and Aroldis Chapman. Are they lefties? Yes. Are they relievers? Yes. Are they good? Yes. But you’d really never call them “good lefty relievers.” They’re just good relievers. (There are also, of course, plenty of other things you could call those two particular people, but I digress.) Speier’s probably not as good as either of them, and he’s only been great in two years, interrupted by an injury year, rather than a whole career. But at this point, Speier has pitched well enough for long enough to at least be talked about more like them than like a glorified LOOGY.

So it rankles that after being deeply underrated, Speier finally stepped into the national spotlight this October only to have essentially all the conversation revolve around his status as a lefty. Most prominently, we were treated to a weeklong debate about how the Mariners could survive Kerry Carpenter. But Speier is no specialist, and while it’s nice that at least he has a reputation at all now, that reputation ignores the changes he’s made to become one of the game’s very best relievers, full stop.

If you really insist on the lefty qualifier, you’d have to describe him as elite, not just good. 362 pitchers threw at least 20 innings last year. When facing lefties, Gabe Speier had a strikeout-to-walk ratio of 21-to-1; that’s behind just one of the other 361 pitchers, and that guy just won his second consecutive Cy Young. I’m not going to belabor the point: If all Gabe Speier amounted to was a lefty specialist, you’d have to say he’s at the top of the heap. And while he was less effective as he played through injury in 2024, this is consistent with his results from 2023.

But he took a big step forward in 2025 by improving his attack against righties. Last year, 206 relievers threw at least 750 pitches, at least 100 of which were to right-handed batters. (I used some uncommon thresholds to create the right sample because it was hard to get the data I wanted while using an IP minimum, but please bear with me while I continue to learn to code. Maybe if you bug him, Ryan will tutor me. The important thing here is that the sample of pitchers I’m using here is ultimately the correct pitchers if you look at the names.) Speier struck out 30.5% of the righties he faced, while walking 6.9% of them. That’s a strikeout-rate-minus-walk-rate of 23.6%, which is good by any standard. It ranks 31st out of the 206 relievers in the sample. In other words, on his weak side, Speier is better than 85% of his peers. And among the 30 pitchers ahead of him, Speier’s .340 xwOBAcon was in the top half, so it’s not like he was giving this all back by surrendering loud contact.

If all Speier did last year was face right-handed hitters, while everyone else faced both righties and lefties, Speier’s FIP would have been in the 93rd percentile, two spots behind Andrés Muñoz and two spots ahead of Griffin Jax. No doubt, Speier is better against southpaws than northpaws, but this is a strength and a strength-that’s-a-little-weaker, not a strength and a weakness. David Bowie was a better singer/songwriter than actor, but have you seen Labyrinth? 

Without going in depth, the big change Speier made is hardly difficult to identify: facing righties this year, he cut his sinker rate in half and his slider rate by a third, which allowed him to essentially double his four-seam usage. It’s just another case of a Mariners reliever identifying a pitch that works and using it more often.

Put together his elite stats against lefties and his still quite good stats against righties and Speier’s 2025 resulted in a FIP- of 57, which was 15th among the 325 relievers who pitched at least 20 innings. Breaking out the most important pieces of FIP, his K%-BB% was fourth, in a top five that also includes Mason Miller and Edwin Díaz as well as, what do you know, Hader and Chapman. That’s not a good lefty reliever, but simply one of the game’s best bullpen arms.

To be sure, the centrality of his handedness in October’s national conversation had more to do with how Dan Wilson was going to manage the pitching staff as a whole to get tough lefties out than it did with Speier’s talents. But the focus still sold Speier short. That was predictable: If there’s been a theme in my writing about Speier, it’s been that he’s underappreciated. I used his 2024 40 in 40 to urge you to join his fan club, which of course you did, and earlier this year, I pitched his case to make the All-Star team, which of course he didn’t.

But at least there’s a national conversation about him at all. Justin Klugh put the sentiment well when previewing the ALDS for Baseball Prospectus: “A guy named Gabe is also one of the best relievers in baseball, apparently.” That reflects Speier being underappreciated but it’s a long way from Jeff Sullivan’s only Speier reference in his 1,500-word write-up of the Shelby Miller trade: “[Arizona] also got Gabe Speier, who is a player.”

Gabe Speier deserves more respect, but he also earns it as he proves himself. Recall how disrespectful Cal Raleigh was in Speier’s first season with the team:

But Cal came around. You couldn’t make a similar supercut from last year. If Speier repeats his 2025, it’ll be the third year out of four in which he performs as one of the game’s best relievers. At some point, people will have no choice but to notice.