Here’s where we are with the state of pitching in 2025: Let’s bring up a pitcher who throws two different fastballs that both have 100 mph velocity but with slightly different movement patterns. But we're mostly going to ignore those heaters, because neither is the pitch that makes him stand out right now.
Lots of pitchers throw hard, after all. But for Arizona’s Justin Martinez, the eye-popping fastball velocity isn’t what caught our attention. It’s the 90 mph splitter, the one that’s thrown with such low spin that at times it resembles a high-speed knuckleball or forkball more than anything. No less a hitter than Aaron Judge discovered this on April 1 while Martinez was in the midst of striking out the side.
That individual pitch, at 90 mph and 555 rpm, is something like a unicorn in pitch-tracking history. It’s one of only seven times that anyone’s ever thrown a splitter that fast with that little spin, and five of the previous times were from Aroldis Chapman, arguably the most legendary hard thrower of his time. (Bonus points if you guessed the other name: Former Red Sox reliever Hirokazu Sawamura, who threw exactly one of these in 2021.)
Martinez, 23, and the recent recipient of a five-year contract extension, is off to a strong start for Arizona, striking out nine without a walk or run allowed in six appearances. He’s whiffed 42.9% of the batters he’s faced, an elite figure should he keep it up all season long.
But even in a world where strikeouts are generally the truest measure of a pitcher’s skill, there’s a different leaderboard that Martinez is atop of right now – and it tells us a little something about how that splitter and the triple-digit fastballs work together. Of more than 300 qualified pitchers so far, Martinez is the only one who has yet to allow a single squared-up ball, meaning whether a hitter actually achieves the exit velocity available to him on a given swing.
Put it all together, and you have a pitcher striking out nearly four of every 10 batters he's faced, with everyone else beating weak contact into the ground, as befits a 90.9% ground-ball rate.
So what is this pitch, then?
It's not a high-velocity "splinker," like the splitters of Paul Skenes and Jhoan Duran, which share similarities with sinkers. It’s not your traditional “grip it hard and watch it dive” pitch, the ones that have led to accomplished careers for the likes of Kevin Gausman and Kirby Yates.
Coming in at 630 rpm on average, it’s got slightly less than half the spin of a Major League-average splitter, and that’s down from where Martinez himself was at last year; this year’s version spins only 77% as much as last year’s. This year, it has the second-lowest spin of any splitter behind only Roki Sasaki’s own unicorn pitch.
It is one of the lowest-spin splitters on record -- but remember, it’s coming in at 90 mph. Lower-spin splitters through the years have generally been more low-80s floaters, like this one (Luke Barker, 82 mph) or this one (Richard Bleier, 80 mph). Faster splitters, like the 93 mph version Jeurys Familia threw in his best years, had considerably higher spin rates, more in the 1,700 rpm range.
That all leaves us with this, dating back to 2008:
- There have been 656 pitcher-seasons with at least 10 splitters thrown
- Only 7 have a lower spin rate than Martinez this year
- All of those 7 threw considerably slower, between 78-86 mph
It's safe to say, then, that this is the most extreme combination of high speed and low spin for a splitter we've ever really seen, particularly since Sasaki's is coming in at 85 mph.
It’s not, necessarily, a 1:1 relationship that “low spin = good” for splitters, but the point here is the outlier nature of it. Every pitcher is trying to have That One Weird Trick, whether it's related to velocity, release point, movement, arm angle, deception, or a combination of those. These days, anything average is, essentially, doom. This is anything but average.
What the spin does help do is lead to some unpredictability. Martinez has thrown 17 splitters so far this year, with the horizontal movement ranging from 2 inches to 17 inches. Gausman, for example, throws almost all of his between 15-23 inches of break. Tanner Houck, another splitter artist, is relatively consistent as well – almost everything between 9 and 18 inches. It can lead to some command problems, to be sure, but if you can get weird movement at great speeds, it’s hard to square up, or even touch.
You can really see what happens when that unpredictable splitter is paired with one of Martinez's 100 mph heaters, neither of which have terribly great shape. (In a 10-inning cameo in 2023, his four-seamer was crushed, allowing a .423 average and .731 SLG, because it has no meaningful rising action, and that’s what led to the introduction of the slightly different sinker in 2024.)
Consider what happened when Martinez faced Judge, arguably the most dangerous hitter of his generation.
After Judge watches a rarely-thrown slider (92 mph) in the dirt for ball one, Martinez fires a 99 mph sinker that starts down the middle and breaks back in toward Judge’s hands, taken by Judge for a called strike. On 1-1, Martinez follows with a nearly identical pitch, this time at 100 mph, and Judge is late, fouling it back for strike 2.
He’s seen the sinker, twice, and the slider, but not yet the four-seamer or the splitter. On 1-2, Martinez unleashes the splitter, and it’s a great one; it’s the 555 rpm one we shared above. It’s 10 mph slower than the sinker Judge just saw, but it drops 16 more inches by the time it gets to the plate. Judge is more than a little early on the swing:
Martinez isn't the full-time closer in Arizona, because A.J. Puk is there too, and because sometimes you'd rather have him face Judge, Jazz Chisholm Jr. and Anthony Volpe in the eighth inning and let someone else deal with the softer bottom of the lineup, as Torey Lovullo did on April 1. But "most saves" doesn't mean "nastiest reliever" anymore, if it ever did. It's quite nice to throw 100, obviously. It might be game-changing to pair that with a pitch like this.