Ranking the 4 best pitches on Mariners' staff for 2026

This marks another year of the Mariners having one of the best pitching staffs in baseball. They have so much talent that their rotation's current alignment is practically a flex, and it's a major driver behind the team's lofty projections for this year.

With such a depth of pitching excellence, it can be hard to identify who has the most lethal weapons on the mound but based on results and stuff, here are a few that stand out.

These are the best Mariners pitches of 2026

4. Luis Castillo's Four-Seam Fastball

During his time in Cincinnati, Castillo was a relatively unique starter, largely depending on his changeup to get by and having a narrower arsenal than most. After he was traded to Seattle, he switched things up by prioritizing his heater and letting his changeup usage gradually decrease over the years.

As a result, his fastball has comfortably become his best pitch. At first glance, none of its intrinsic characteristics necessarily stand out. It has an average velocity of 95 mph, and its induced vertical break is just 12 inches, making it relatively flat. However, because of Castillo's low arm slot and ability to consistently command the pitch at the top of the zone, it remains effective even if its stuff isn't the most compelling.

Nonetheless, it held opposing hitters to a .203 average and had a 26.5 whiff rate in 2025. The pitch will continue to be his workhorse and it may even see some gains in velocity over the course of the season, potentially making it even better.

3. Eduard Bazardo's Sinker

Last season, Bazardo's chase (23.2) and whiff rates (19.4) were in the bottom decile of qualified pitchers. Yet, he still managed a respectable 26.2 strikeout percentage. How is this possible?

Although he wasn't missing many bats or getting opposing hitters to expand the zone, his sinker gave him called strikes to make up the difference, especially in two-strike situations. The putaway percentage, or rate of two-strike pitches that result in a strikeout, was 29.3 on his sinker, making it one of his favorite finishing tools.

Even when batters did decide to swing, they slugged just .202 against the pitch, struggling to adequately square it up. The shape of his sinker paired incredibly well with the glove-side movement of his sweeper and allowed him to reach new heights in 2025. Assuming he makes additional refinements in 2026, he may continue to climb.

2. Andrés Muñoz's Slider

Seattle's closer has one of the hardest pitches to touch in the sport of baseball. Of all pitch types thrown more than 400 times in 2025, the whiff rate on Muñoz's slider (51.0) was 4th in MLB. If we narrow down the criteria to only include pitches with a run value of 10 or more, indicating few waste pitches, then the only pitch with a higher whiff rate was Mason Miller's slider (54.6).

The main reason it's so effective is that it has slightly more drop and horizontal run than MLB average but it also has very late and sharp break. When tunneling off of his four-seam fastball (and sometimes his sinker), it's tough for opposing hitters to correctly guess what's coming. If they do manage to make contact, the .133 slugging percentage on the pitch illustrates how hard it is to hit with authority.

1. Bryan Woo's Four-Seam Fastball

When Bryan Woo debuted in 2023, his arsenal was extremely fastball-dominant and he struggled to find a secondary pitch that was as effective. Now, he still doesn't have an elite breaking or off-speed pitch but his heater has become so good, he hasn't really needed one, even as a starting pitcher.

On paper, this is mind-boggling because the pitch seems average both in terms of movement and velocity. Like Castillo's, Woo's fastball is thrown from a relatively low arm slot of just 25 degrees and its 10 inches of arm-side run is more impressive than the 15 inches of induced vertical break.

However, Woo's formula for success elevates Castillo's to the next level thanks to his high vertical approach angle. The perceived "rise" in a fastball can be achieved in several ways, two of the most popular being to locate it up in the strike zone and maximize induced vertical break.

For Woo, his low release point makes the pitch far more deceptive and even if it looks like a meatball or a waste pitch outside of the zone on television, it's far more imposing from the batter's box. Logan Gilbert said as much last year in a conversation with Shannon Drayer of Seattle Sports about what exactly makes the pitch such an effective tool.

Bryan Woo was one of the best starters in baseball last year, posting a 2.94 ERA and finishing fifth in AL Cy Young voting. He'll be entering his fourth big-league season and because he only continues to get better, his still undiscovered ceiling may be higher than fans can imagine. His lack of an equally effective non-fastball offering may come to haunt him later down the line but for now, his four-seam fastball is all he needs to succeed.