(AP Photo/Alex Brandon)

Drew Storen knew he worked best when he pounded his fastball with aggression, when he did not nibble at the edges of the plate and jumped ahead in counts. But there was a problem. He relied exclusively on a fastball and a slider, one hard pitch and one offspeed. Hitters could identify which one Storen was throwing. They started to crush his fastball when he threw it early in counts, which forced him to try to be perfect with location.

This year, expanded use of his semi-new change-up has solved Storen’s problem and helped make him one of the most dominant relievers in baseball. In 14 1/3 innings, including a 1-2-3 seventh Sunday, Storen has allowed seven hits and one walk while striking out 15. His 0.56 WHIP ranks second among big league relievers. Ten months ago, the Nationals demoted him. Today, he’s a lodestone in their bullpen’s backend.

The biggest difference has been the much-discussed delivery alteration Storen made during his time at Class AAA Syracuse last year. Storen has also been throwing his change-up more frequently. This year, he’s thrown it 11.9 percent of his pitches, enough to keep hitters from cheating.

“That’s helped me in fastball counts sometimes, especially first pitches,” Storen said. “Guys can ambush me sometimes. It’s really helped me, and kind of helped not really nibble on my heater and have to throw the perfect pitch.”

If a hitter wants to guess Storen will throw him an offspeed, he has to choose between his trademark slider or the change. If a hitter sees a pitch with fastball action coming out of Storen’s hand, he can’t be sure it’s not the change-up. Storen’s change moves just like his sinker, just seven miles per hour slower and with more break at the end.

“I think in general, it’s just about making them feel uncomfortable more than anything,” Storen said. “If they’re guessing fastball and I throw them a change-up, it puts it in their mind. They can’t eliminate pitches against me. I think that’s the number one thing.”

“This year it’s a pretty good pitch,” catcher Wilson Ramos said. “It’s very different when you throw only a fastball and a slider. The change-up is a pretty good pitch. It’s one of the hardest pitches to hit. You can change the hitters mentally.”

Storen developed the grip for his change-up in 2012, monkeying around while he was on the disabled list. He debuted the pitch late that season, but rarely used it. He threw more and more change-ups late last year. Stephen Strasburg uses his change-up similar to Storen, as a tool to keep hitters from attacking his fastball early in counts, and Storen studied him.

“It’s been huge,” Storen said. “I’ve been able to use it against lefties, and I think that’s been a great tool for me, being able to throw it for strikes and keeping that thing down.”