How rare lefty splitter has helped fuel Shota Imanaga’s historic start for Cubs

CHICAGO — Five years ago in Japan, Shota Imanaga searched for a new pitch.

He wanted to incorporate something that would use the same arm path as his four-seam fastball. Imanaga didn’t like his tendency to pull his arm down when throwing change-ups, so he tinkered. The left-hander landed on a split-finger grip that felt good in bullpen sessions, and eventually he threw it in games.

Once he saw Nippon Professional Baseball hitters’ reaction to the splitter, Imanaga knew he had a potentially great pitch.

Since he joined the Chicago Cubs rotation this year, Imanaga’s splitter has been nearly unhittable with a 47.7% whiff rate and a .177 expected average. San Diego Padres hitters whiffed on 15 of the 24 splitters they swung at from Imanaga in the Cubs’ 3-2 walk-off win Tuesday night. Jurickson Profar’s two-run homer in the eighth inning — well-located down and out of the zone — was only the second extra-base hit Imanaga has allowed on the pitch this season.

The splitter has played a key role in the must-watch beginning to Imanaga’s major league career. His 1.08 ERA leads all starters, and only two pitchers since 1913, when earned runs became an official statistic in both leagues, had a lower ERA through seven career starts: the Boston Red Sox’s Dave Ferriss in 1945 (0.57) and the White Sox’s Cisco Carlos in 1967 (0.89).

The nastiness of Imanaga’s splitter goes beyond his elite command. Big league hitters aren’t used to seeing lefties throw the pitch.

Only 16 lefty starters have thrown a splitter since the start of the 2008 season. Five of them — Jorge De La Rosa, Manny Parra, Aríel Miranda, Randy Johnson and Erik Bedard — threw more splitters than Imanaga has, according to Baseball Savant. But no lefty in that span came close to using it as frequently as Imanaga relies on his splitter, which accounts for 30.3% of his pitches thrown.

Even when expanding to include lefty relievers, Imanaga already has thrown the 13th-most splitters over the last 17 seasons and ranks second in percentage of splitters thrown.

“For me the splitter being effective and dangerous, it’s a fine line because if I miss, then the hitters are a lot stronger here so they’re going to hit it further,” Imanaga told the Tribune through interpreter Edwin Stanberry. “But the most important thing for me, since I do throw my fastball up in the zone, having that in the hitters’ head is effective because then I can go up and then down low.”

Although he uses a splitter grip, Imanaga thinks of the pitch as a change-up. When on the mound, he doesn’t feel like he’s throwing splitters, a mentality that seemingly helps him throw it for strikes.

“Honestly, it’s never really taught a whole lot to lefties, and so for him, it is such a unique pitch and the ability to throw it with a lot of depth,” Cubs pitching coach Tommy Hottovy said. “It’s always going to be a unique weapon.”

Left-handers tend to naturally pronate and work inside the baseball, so a change-up is typically an effective pitch. Cubs lefties Jordan Wicks and Drew Smyly, armed with change-ups, are good examples of that.

Smyly understands how difficult harnessing a good splitter can be for a left-hander. He added the pitch to his repertoire while working out at Driveline Baseball in the offseason, and though he used it in spring training outings, he hasn’t needed it now that he’s pitching out of the bullpen. Smyly marvels at Imanaga’s splitter.

“That’s why it’s so effective: It looks like a fastball for so long and you just rip it like a fastball, then it has crazy action,” Smyly said. “You never know if it’s going to go this way or that way. It’s a very fun pitch but also a very hard pitch to throw.”

When scouting Imanaga, the usage and effectiveness of his splitter was something president of baseball operations Jed Hoyer and the Cubs hoped would translate well against major-league hitters. The organization also was uncertain how well Imanaga could control his repertoire to fill up the zone.

Through seven starts, Imanaga has walked only five batters while striking out 43. No other starter has posted an ERA as low as Imanaga’s with that few walks through seven career starts since 1913, according to researcher Sarah Langs. Paired with his heater, the splitter-fastball combination has neutralized big league hitters.

“He’s done a great job of playing the high-low game — fastballs up and splitters down has been really effective,” Hoyer said last week. “Just in general the strike throwing. You never know, when a pitcher is coming from Japan and having a different ball and a different strike zone, how the command is going to be, and his command has obviously been excellent.”

Imanaga’s unique rising fastball characteristics — and his ability to tunnel his splitter off of it with similar release points — force hitters to change their sight lines significantly with the difference in vertical movement. His splitter averages 32.3 inches of drop, 4 inches more than league average for already limited looks against the pitch, while his fastball has 13.2 inches of drop, with 3.4 inches more rise than average.

The inherent vertical separation between a fastball and splitter is taken to an extreme with Imanaga, adding to hitters’ challenge. They have to pick which one to commit to in the batter’s box to help them focus on one part of the zone. Even then, Imanaga’s command of the two pitches has limited chances for damage.

“The arm action never changes,” veteran catcher Yan Gomes said. “And he throws the splitter for a strike, so it becomes another pitch to have instead of, oh, it’s going be a punchout or chase. He can do that, but it’s almost like, lay it in there change-up style and then (he) can bury it. The arm speed and how he does it is really cool.”

Hitting coach Dustin Kelly feels fortunate the Cubs don’t have to build a game plan to face Imanaga.

“He’s just got confidence and an aura about him,” Kelly said recently. “That translates, and when you see a guy bouncing around the mound like that and coming at you with his best stuff at all times, it’s like, all right, this guy’s here, we better go attack him. You’re seeing guys just miss pitches that they probably think they should hit.”

The numbers don’t lie when it comes to Imanaga’s effectiveness to begin his major league career. Although he is considered a rookie by MLB standards, he brings eight years of professional experience and knowledge from Japan. He recently declared he will wait and let hitters determine whether he is a dominant pitcher in this country.

Even after a torrid start with another lights-out performance Tuesday, Imanaga isn’t ready to acknowledge how he has been one of the best starters in the majors.

“I think it’s going to take a long time,” he said. “I try not to think I’m a good pitcher because when I do, I feel like I’m going to relax a little bit, ease up a little bit. I want to keep going and working hard.”