Justin Martinez’s immaculate inning was electric, but it’s only the start of what’s to come for the flamethrowing right-hander.
In last night’s win over Texas, Martinez tossed the fourth immaculate inning in Diamondbacks history. He induced one foul and five whiffs, in addition to dotting three called strikes. The Dominican native topped out at 102.6 mph while sprinkling in three beautiful splitters. His 34.4% career whiff rate came into play, as the Rangers’ trio of Wyatt Langford, Evan Carter and Jake Burger could hardly even see his offerings.
Justin Martinez pitches an IMMACULATE INNING! pic.twitter.com/UzNjg4Tu4y
— MLB (@MLB) September 12, 2026
Martinez entered the league back in 2023 as a hard-throwing strikeout artist with command issues. He walked 11 batters in 10 innings but struck out 14. He found his footing in 2024, posting a stellar 2.48 ERA over 72.2 innings out of the bullpen. Martinez posted excellent underlying numbers, including whiff and barrel rates in the top 5% of all pitchers.
However, a second Tommy John surgery cut short Martinez’s rise. He missed the majority of 2025 and well into the 2026 season while he recovered. Since returning on Aug. 8, it’s been right back to business for J-Mart, as he’s yet to allow an earned run in his eight games back.
Beyond his success, Martinez is simply one of the most fun pitchers to watch solely because of his wicked pitch mix. He sits around 101 mph on his fastball and throws what is virtually a 90 mph knuckleball.
Pure heat and turbo-knuckleballs?
Martinez’s bread and butter is predictably his high-velocity fastball. He throws both a two-seamer and a four-seamer, neither of which has dipped below 100 mph this season. His sinker favors more horizontal break (15 inches of horizontal break), while his four-seamer maximizes vertical ride (14.3″ of induced vertical break).
His four-seamer induces whiffs on 42.1% of swings, and opponents are averaging just an 81.9 mph exit velocity against the pitch. They’re batting .111 against it without a single extra-base hit.
However, his most intriguing offering is actually his splitter, which simply breaks baseball convention. His split-finger comes in at 90.3 mph, much harder than the league average of 87.0 mph. But that’s not nearly the craziest part.
Martinez’s splitter is virtually a 90 mph knuckleball. The typical spin rate for a knuckleball ranges from about 300 to 800 rpm. On average, his splitter reads 694 rpm, according to Statcast. Visually, the pitch drops almost inexplicably from its trajectory.
It’s extremely different from a sweeper or a curveball, where a batter can pick up the consistent spin of the pitch quickly. Martinez’s splitter is so unpredictable that it’s posting a 43.8% whiff rate. In 2024, it posted an unreal whiff rate of 54%. For his career, more than half of all swings against his splitter come up empty. Very, very few pitchers can say such a thing about one of their pitches.
So while he throws heat, he’s also somewhat of a magician with his splitter. He’s truly one of the most entertaining relievers out there, and he’s still just scratching the surface of what his wicked arsenal can accomplish.
If the Diamondbacks finish out strong, there’s a good chance Martinez makes a name for himself in October. He has all the tools. He’s just waiting for his opportunity to show the world the electricity in his right arm.
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