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Over the past four years, Tyler Clippard has used a steady formula to become one of the most reliable and durable relievers in baseball. He thrives on high fastballs and a disappearing, fading change-up, with a few cutters and curves sprinkled in. The combination produces strikeouts and flyballs by the bushel. It has made him an often-dominant set-up reliever and a very rich man.

But Clippard has recently tinkered with the formula. In September, he has thrown seven splitters, a pitch he has long toyed with but, until this month, had never thrown in a major league game. He plans on adding to his repertoire as a regular weapon. He just needs to figure out how.

“I wouldn’t have thrown it in the game if that wasn’t the case,” Clippard said. “I just basically have to figure out when I want to throw it. It’s tough, because I had four pitches before, and now I have another one. And it’s too many. It’s one of those things where, I know it’s a good pitch for me. How I incorporate it is the tough part. It’s a work in progress.”

Clippard had never shown his splitter with the Nationals, but he has thrown it for years. When he first arrived in the pros, in rookie ball, he threw the splitter. Back then, he used a lower arm slot, and he had trouble controlling the pitch – sometimes it would dart like a slider, and sometimes it would fade like a slower sinker.

“I didn’t know where it was going, so I stopped throwing it,” Clippard said. “And I had a good change-up. So I didn’t need it. But, you know, it’s something I’ve been fiddling around with for a few years.”

Clippard continue throwing the splitter in bullpen sessions and while playing catch with fellow pitchers before games. The pitch takes little finesse to throw. The pitcher uses the same grip as a two-seam fastball, with his fingers spread out wider, almost on the sides of the ball. It causes the ball to move slower than a fastball but harder than a change-up and dive as it reaches the plate.

“If you can throw it, you can throw it,” Clippard said. “And I’ve always been able to throw it.”

And so, even as he used it little during games, it managed to impress teammates. It darts down and travels about three mph faster than his curveball.

“Everyone is telling me, ‘That’s a great pitch. You need to throw that,’ ” Clippard said. “They kind of built my confidence up with it. I knew it was. But I had four pitches already. What do I need that one for?”

One reason: Clippard is an extreme flyball pitcher – only three qualified major league relievers have a lower groundball rate than his 28.2 percent this season. The downward action of his splitter would help him induce more grounders, which in turn would lessen his susceptibility to home runs.

“I’m always trying to get better,” Clippard said. “I feel there’s certain things about who I am as a pitcher than can improve. But I can’t let that go the other way, too. I’ve seen that happen to guys. I think it’ll be a good pitch for me in certain spots. But I don’t feel like I need it. I’ve had success without it. If I incorporate it the right way, it can be very effective for me.”

On Sept. 7 in Miami, Clippard entered in the eighth inning to protect a five-run lead. He decided it was time to test out the splitter. He threw one to Donovan Solano and another to Chris Coghlan, both on 1-2 pitches. They both grounded out against the splitter, just as Clippard had hoped.

Afterward, Clippard made an interesting discovery while watching video. He got the result he wanted, but he realized the pitch had not been all that great. He relies on precision with his change-up. With the splitter, he had made a mistake, but the downward bite on the pitch saved him.

“I don’t have to really locate it well for it to be an effective pitch, which is why I like it so much,” Clippard said. “It did what I wanted it to do. They weren’t really that good pitches. They were kind of up in the zone, kind of right down the middle. But the swings that I got off them were bad swings. It makes me think that was a good pitch. Now I just have to figure out when to incorporate it.”

A week later at Nationals Park, Clippard entered in the eighth with the Nationals down one run, a crucial situation. He retired John Mayberry with a splitter, which he grounded to short despite the pitch being up in the zone. Clippard then whiffed Domonic Brown with a splitter up and out of the zone. Both hitters seemed baffled Clippard had thrown it.

“They were probably like, ‘What the frick was that?’ ” Clippard said. “Which is another thing that I like about it. It’s another pitch they have to think about. Anytime you can get up there and have the hitter kind of just being like, ‘Now what is he going to do?’ that’s a good thing.”

Clippard knows his splitter can help him, but he still need to work on how often and when to throw it. He has already established himself, and he does not want to change what has made him successful. But the splitter could become an effective complement to an already befuddling arsenal.

“That’s the fine line,” Clippard said. “If I throw that more, will this suffer? I don’t want that to happen. That’s why I have to figure out how much I want to incorporate it or not.”

Much thanks to our resident Pitch FX maven Harry Pavlidis, who pointed out Clippard’s usage of the splitter to me.