The way Luis Castillo dominates may look mighty familiar to Mariners fans

This is one of the easiest articles I’ve ever set out to write. RHP Luis Castillo, who is a Seattle Mariners starting pitcher and will take on the New York Yankees today, is one of the best pitchers in all of MLB. You can measure that by any number of metrics, as a 2.86 ERA and a 3.20 FIP are shiny enough, but there’s more to fawn over.

When your numbers are in line with those of Gerrit Cole, Justin Verlander, Yu Darvish, Shohei Ohtani, and Clayton Kershaw, depending which of the metrics above you fancy, you’re among the class of the league. Castillo’s typically been a tier or half a tier below names like those; however, his time in one of the league’s great offensive band boxes on a mostly uncompetitive Cincinnati Reds club has kept him from ascending entirely. All-Star appearances in 2019 and 2022 were interrupted by a down 2021 and a 2020 where he still continued dealing in the shortened season. Despite missing the first month of the season, he’s returned and quickly reclaimed his workhorse status, working 7.0 innings in each of his last four outings and not failing to eclipse at least five frames since his first outing of the season. Oh, and when the chips are down, he pulls out things like this:

Earlier in his career, Castillo was one of the league’s preeminent groundskeepers. Among the most effective groundball pitchers around, Castillo leaned on a trademark hard changeup, a solid slider, and a pair of fastballs he used reasonably evenly, albeit always leaning more to his four-seam. The changeup was of the caliber that it has earned its own highlight reels.

Sitting 87-90 mph, Castillo’s firm cambio still maintains a traditional 8-10 mph gap off his heaters, but as such a heated biting changeup, may conjure up memories of another firm changeup savant.

Seattle has had slow-mo masters since King Félix left the building, but Marco Gonzales is very much a different type of changeup thrower. Castillo, like Félix Hernández could, can lean on the changeup in any situation.

This year, however, the pitch is his primary offering to lefties, while a more complementary offering against righties. For the first time since 2018 it’s no longer his primary (or at least plurality) pitch. It’s been superseded by his refined four-seamer, which Jake Mailhot wrote up brilliantly for FanGraphs just before the trade deadline. To summarize a few key points of Jake’s analysis, not only does Castillo continue to average 97 mph on his heater, but he has significantly adjusted the utilization and presentation of the pitch. Specifically, from Castillo’s functionally sidearm release point, Castillo is pumping high heaters that appear to rise or hover with run to hitters. The concept of Vertical Approach Angle (VAA) is highly in vogue among clubs because teams have realized a four-seam released low to the ground that heads to the top of the zone creates even more significant “rising” effect. From Jake’s article:

FanGraphs / Jake Mailhot

Because Castillo delivers his four-seam from a low point compared to most pitchers, as well as extended out to his right, the pitch hardly has the quintessential pure backspin oft-prized by clubs. However, with its consistent location, the UFO-ball with nearly horizontal rotation floats and runs, making it do its best flying saucer shimmy away from bats. The concept tracks for anyone who has tried to hit a rising wiffle ball, a process that is antithetical to all expectations hitters train for their whole lives. This is a fairly similar fastball to a few pitchers Seattle has already developed, most notably Paul Sewald, Andrés Muñoz, Matt Festa, and Matt Brash. Here’s a collection of their four-seam spin and locations; without knowledge of the velocity or release points you’d have reason enough to think you’re getting a similar look:

Baseball Savant

All of these pitches have been extremely effective (with the possible exception of Muñoz), even as each pitcher is rightfully known for their off-speed pitches, as they are able to subvert expectations from hitters and get swings that skim underneath the bat. Of the 262 pitchers with at least 200 four-seamers thrown, all of that group save Muñoz rank in the 75th percentile or better in Called Strikes plus Whiffs rate (CSW%), per Alex Chamberlain’s spectacular leaderboard, including Castillo 9th overall and Festa 1st(!!). Moreover, we can see that the VAAs of each pitcher are among the lowest (read: flattest) in all of MLB.

Alex Chamberlain

This means that like Sewald and co., Castillo delivers his four-seamer consistently at or above the upper third of the zone, released from a low enough angle to augment the damning optical illusion of a rising pitch to hitters and generate swings and misses in bunches. Except instead of like Sewald and Festa, he throws 96-100 instead of 91-94, and instead of throwing it where he aims it on occasion like Muñoz and Brash, he is more consistently locating, and doing so with not just the heater but with his changeup and slider to boot. Oh, and unlike any of these relievers, he does this for 6-7 innings per outing.

If the adjustments to his delivery have a cost, it seems that Castillo may be suffering a slight loss in angularity on his sinker and changeup by extension. Both pitches inversely to four-seamers, are more effective the lower they are in the zone, and the more steep of an angle they are delivered at. This has been common knowledge for a century - a taller pitcher is always prized because of the steep plane they can generate on their pitches to shrink the zone over the plate at which a hitter’s barrel and the ball are traveling in alignment.

Of course, this specific conceit was part of the crux of the fly ball revolution and the proliferation of swings designed to scoop sinkerballers like Castillo and the erstwhile King Félix over the fence. So pitchers have had to adapt or die, and as was noted by Aidan Resnick of Pitcher List, Castillo’s willingness to adapt despite his track record of success is emblematic of a great pitcher. I’ve scarcely touched on the 29-year-old’s slider, which is a stellar offering in its own right that generates whiffs over a quarter of the time and is his best weapon against righties, nor his atypically flat sinker that is his most hittable pitch, yet is barely ever barreled and still helps him get ground balls almost at will, perhaps managing to work around the constraints of his new delivery and release point. This is an ace with three above-average pitches, including a pair resembling Mariners greats of yore and present, dominating and shouldering heavy workloads with excellence and flair.

We’re gonna like the way it looks.