FORT MYERS, FLA. – Watch Griffin Jax during a live batting practice session, and it's easy to understand what makes him one of the most dominant relievers in baseball.

The velocity and movement on Jax's pitches are incredible, even to big-league hitters. One batter, after a live BP, reminded Jax that he didn't strike him out — never mind the result of his simulated at-bat was an infield pop-up.

But the filthiest pitch in Twins camp? No, it wasn't Jax or Jhoan Duran's unique splinker. It doesn't belong to Pablo López or Joe Ryan, either.

A poll of the team's seven catchers in spring training identified a surprise winner.

"I think we have a new one," catcher Patrick Winkel declared before a recent spring training game. "The Cory Lewis knuckleball."

All the guys with experience catching Lewis seemingly have a story about their first time seeing his knuckleball. When Alex Isola caught a Lewis bullpen session last year, Class AA teammate Andrew Cossetti warned him: "Don't raise your glove early. It's going to drop more than you think."

"I'm like, all right, whatever, I'm sure it's not that big of a deal," Isola said. "First one, I almost missed because I went to pull my glove up and at the last second, it just dove. I was lucky it didn't hit me in the [groin], honestly."

Winkel wasn't as fortunate. "The last one he threw in warmups," he said, "hit me square in the face."

Lewis, the Twins Minor League Pitcher of the Year in 2023, posted a 2.59 ERA in 15 outings at Class AA Wichita last year with 80 strikeouts and 34 walks in 66 innings. Unlike traditional knuckleball pitchers, Lewis throws his knuckleball around 85 mph, and it's used in combination with his fastball, slider, curveball, cutter and changeup.

The pitch might not float like slower knuckleballs, but it can still dart in any direction. It makes it just as tough on catchers as hitters.

"It feels like someone is throwing a ball at you and then someone is shaking you really hard," Winkel said.

Lewis, 24, bought an oversized catcher's mitt after the Twins took him in the ninth round of the 2022 MLB amateur draft, which he passes along to anyone who catches him. Catchers joke that it looks like a softball first base mitt, but it's absolutely necessary.

"You have no idea what it's going to do," Winkel said. "You can't really get on someone for not catching it because it's like, 'Well, why don't you get back there and try?'"

Lewis threw 13 knuckleballs in his Grapefruit League debut last week against the Detroit Tigers, the first time Jair Camargo had an opportunity to catch him. The PitchCom device that allows catchers to call pitches didn't have knuckleball programmed into it, so Lewis and Camargo settled on calling it a "sinker" in the earpiece.

Tigers batters swung and missed on five of their eight swings against the pitch. When Gleyber Torres, a two-time All-Star, fouled one knuckleball, Camargo thanked him because his catcher's mitt was out of position, and he thought it would have struck him.

On the next pitch, another knuckleball, Torres whiffed on an awkward strike three swing as the ball hit Camargo flush on his left thigh.

"Lucky me, I only missed one," Camargo said. "It's gross, man, catching him. The movement is different, but he's able to throw that for a strike and a chase pitch. I think he's the nastiest guy."

San Diego's Matt Waldron is the only current pitcher in the big leagues with a knuckleball, though his averages 77 mph. Lewis will likely start the season at Class AAA St. Paul.

Is it fun to catch one of the sport's few knuckleballers?

"As long as it doesn't leave bruises," Winkel said. "Ask me after I catch it to see if I had a good time catching it."

A reporter asked Camargo if he ever faced Lewis' knuckleball as a hitter during camp. Camargo immediately shook his head, no, before offering a two-word response: "Thank God."

Honorable 'filthiest' pitches

Eiberson Castellano's curveball: The Rule 5 pick is competing for a spot in the Twins bullpen, and his curveball that reached 83 mph Friday is his best swing-and-miss pitch. "It's not often a guy can throw an upper-80s curveball," Ryan Jeffers said. "That's pretty impressive when you can."

Zebby Matthews' pitch mix: The one certainty with Matthews is he will throw strikes. He's walked only 22 batters in 205 career minor league innings. Christian Vázquez said Matthews looks "electric" with his velocity up in his first Grapefruit League starts. "Nasty stuff. He's working on a changeup and it was looking good," Vázquez said. "The fastball was 97 mph in the first game of camp. To see that, it was like, oh my god."

Danny Coulombe's sinker: Mickey Gasper cautioned that he is a part-time catcher in camp, so there are a lot of pitchers he hadn't caught, but the late movement on Coulombe's sinker was impressive. It's a pitch designed to create weak contact. "It was about to be in your glove and then it takes off to your right," Gasper said. "He told me to setup like [pitching] backdoor to a lefty. It started off my body and it ended up off my body to the other side."

Joe Ryan's sweeper: Ryan built his career off a unique fastball that overpowers hitters at the top of the strike zone, but his sweeper created a lot of whiffs last year. "It moves a lot," Diego Cartaya said. "I actually missed it twice. I wasn't expecting it to move that much. I was happy I was catching it and not swinging at it."