An inside look at why Phillies closer Jhoan Duran’s signature ‘splinker’ is such an effective pitch

Jhoan Duran threw his first pitch for the Phillies — and his second, and third, and fourth — by gripping the ball like a splitter and ripping it with the velocity of a sinker.

Behold the splinker.

Wait, a splinker?

“I’ve seen one,” said Caleb Cotham, Duran’s new pitching coach. “Not in person.”

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It’s Duran’s signature. Well, one of them. The Phillies’ new closer, acquired in a trade-deadline blockbuster, has a theatrical entrance, set to a club beat and with scoreboard flames and tarantulas — a nod to his spider tattoo and catchy “Durantula” nickname.

The real show, though, happens once Duran unleashes the ball. His fastball averages 100.2 mph. But in recording a four-pitch save in his Phillies debut Friday night against the Detroit Tigers, he threw only splinkers.

Duran said he discovered the pitch by accident. He was in A-ball with the Arizona Diamondbacks in 2018 when he tried to throw a sinker in a bullpen session.

“I did a little wiggle [with his fingers] with the ball, and I found it, that pitch,” Duran said. “[The grip] is more open. Because in the past I threw a splitter. So, I mix both and I throw it.”

Duran isn’t the only prominent pitcher who features the hybrid pitch. Pittsburgh Pirates sensation Paul Skenes also throws a splinker, though not as hard as Duran’s.

It wasn’t until 2023, Duran’s second full major league season with the Minnesota Twins, that he really mastered the pitch. This season, he’s throwing it nearly 40% of the time and holding opponents to a .221 average, a .286 slugging percentage, and one homer (to Shohei Ohtani). The splinker has generated a 26.5% swing-and-miss rate.

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Cotham explained what makes the splinker so effective, citing three factors: extreme velocity (97.5 mph, on average), unique movement, and precise command.

“It’s kind of holy grail, trifecta type stuff,” Cotham said.

The velocity is what makes everything possible, Cotham says. Most pitchers throw a splitter with less heat than a fastball, usually in the 80-90 mph range. The ones Duran threw Friday night registered 98.4, 99, 99.7, and 98.8, more typical of sinkers.

But the pitch also has the late, downward break of a typical splitter.

“One of the benefits of throwing really hard is you can show pitch types that don’t look like anything else,” Cotham said. “But even if it was 86, I think it’d still be a good pitch by how it moves. The most impressive thing is the ability to hold velocity and have shape that’s à la splitter, which is tough to do. But he’s found a way.

“And then it’s his ability to throw it for strikes. Those types of pitches, they’re hard to command because they do funny things at times. But his control of it is fantastic.

“That, to me, is the difference-maker. There’s a lot of nasty pitches that aren’t necessarily competitive all the time. But his ability to blitz the strike zone with 99 mph splits, sinkers, whatever you want to call it, he’s special.”

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Although recently signed reliever David Robertson is eligible to return Tuesday from a triple-A assignment, he probably will need more time, according to manager Rob Thomson.

The Phillies signed Robertson on July 20 and sent him to Lehigh Valley to build his arm strength. The 40-year-old righty touched 92 mph Friday, but struggled to command his fastball and gave up three runs on three hits and a walk.

“He feels like he’s in the second week of spring training,” Thomson said, “so it’s kind of normal.”

Robertson is slated to pitch again Sunday. He still wants to pitch on back-to-back days and/or get more than three outs in an appearance before coming to the majors.

Fellow reliever Joe Ross (back spasms) also is scheduled to pitch Sunday for Lehigh Valley. He tossed a scoreless inning and dialed up his fastball to 95 mph Friday.

Aaron Nola (rib) felt fine one day after a three-inning, 47-pitch start for Lehigh Valley. He’s scheduled for four innings and 65-70 pitches Wednesday in Allentown. … Lefty reliever José Alvarado, eligible to return from his 8-game PED suspension on Aug. 19, will report to Citizens Bank Park on Monday before going on a minor-league assignment. Alvarado has been throwing on his own during the suspension, Thomson said. ... One week after the late Dick Allen’s induction into the National Baseball Hall of Fame, the Phillies paid tribute to Allen in a pregame ceremony. … Jimmy Rollins and Ed Wade threw ceremonial first pitches after being inducted Friday night into the Phillies’ Wall of Fame. … More than 50 former players are scheduled to attend Sunday’s Alumni Weekend ceremony, including six Hall of Famers (Mike Schmidt, Steve Carlton, Jim Thome, Scott Rolen, Pat Gillick, and Pedro Martínez). Rollins, Chase Utley, Ryan Howard, and Cole Hamels also are on the guest list. … Cristopher Sánchez (9-3, 2.55 ERA) is scheduled to start the series finale at 7:10 p.m. Sunday against Detroit’s newly acquired right-hander Charlie Morton (7-8, 5.42).