FORT MYERS, Fla. -- It's fun for Twins catcher Ryan Jeffers to hear the mumbled reactions from opposing hitters when Jhoan Duran is on the mound.

"You get the, 'Holy ... how does he throw that?'" Jeffers said. "All sorts of reactions like that. You get a lot of hitters looking pretty silly."

Every hitter at the professional level has been honed by tens of thousands -- if not hundreds of thousands -- of repetitions standing in the batter's box with pitches coming at them. They've seen everything there is for pitchers to offer. Any offering they haven't seen before is akin to the proverbial needle in a haystack.

Duran wields that needle. It even has a pointy-sounding name: his "splinker" pitch. Now that he's made his first big league roster as a reliever, count on seeing it often at Target Field when the Twins' No. 6-ranked prospect, per MLB Pipeline, makes his MLB debut.

"It¡¯s not really a one-pitch-wonder kind of deal, but it¡¯s like, there are pitches that only one person has in the game," Twins manager Rocco Baldelli said. "I think this pitch is a pretty unique pitch. I don¡¯t know how you prepare or game-plan or think about a pitch like that as a hitter. I¡¯ve never seen anything like it in my life. I can honestly say that."

So what on earth is a splinker?

The name is a portmanteau of "splitter" and "sinker," and that's really the essence of the pitch. Duran uses a split-fingered grip and throws it as hard as he can, causing it to move like the most violent sinker you've ever seen, falling off the table to his arm side.

He can throw it at the heart of the zone and have it finish in the dirt. Sometimes, he'll aim above the zone and drop it in for a called strike. At the suggestion of a coach within the D-backs' organization before Duran's arrival to the Twins in the 2018 trade that sent Eduardo Escobar to Arizona, Duran started toying with different grips -- until he found the one.

"It was like a normal sinker, but when I got traded here in 2018, I started playing in a bullpen session and [the splinker] came out," Duran said.

"And I was like, 'Oh.'"

More like "oh, no" if you're an opposing hitter.

In 2017, Duran's final full season in the Arizona organization, he tallied 49 strikeouts in 62 1/3 innings. In '19, his first full season in the Minnesota organization, that strikeout count soared to 136 in 115 innings. He struck out 22 batters in 16 innings with Triple-A St. Paul last season while elbow issues held him out of action for most of the season.

This spring, Duran's best stuff is back with a vengeance. He has thrown seven tracked fastballs at 100 mph or harder (not all Grapefruit League parks are equipped for pitch tracking). He mixes in a hard curveball in the high 80s. His 25 tracked splinkers (categorized by Statcast as splitters) have averaged 94.3 mph, twice topping out at 97.

Among the 46 pitchers who threw at least 25 splitters in the big leagues last season, that average velocity would have ranked first.

It'll be tough to properly quantify and contextualize Duran's movement data until he has a bigger sample size in Major League parks with Statcast tracking. For now, you'll have to rely on the testimonial of the guy who's behind the plate for most of those pitches.

"You don't have guys throw something that hard with that much movement," Jeffers said. "It just doesn't happen."

Duran is breaking camp on the Twins' roster despite the lack of an opening in the starting rotation, in part because a bullpen role helps to limit his workload after the injuries of 2021 -- and because his stuff is ready to get big league hitters out now.

The splinker is coming for them.

"You have to prepare for it kind of like a fastball because it¡¯s coming in at 95-plus miles an hour," Baldelli said. "How you deal with that and the ball moving like that is a different story.

"I will let the other team deal with that."