(Photo by Patrick Smith/Getty Images)

Rafael Soriano, the closer who always makes things so hard on himself, made it look so easy Wednesday afternoon. He struck out Matt Kemp swinging at a biting slider over the inside corner, finishing off another 1-2-3 inning. “It’s not easy,” Soriano said, laughing and shaking his head before he exited the clubhouse.

Were you wondering why you forget to fill your blood pressure medication prescription? Though the season’s first month, the excruciating version of Soriano has been replaced by the dominant closer the Nationals thought they had signed last winter. Soriano has yet to yield a run in 13 appearances, and with a WHIP of 0.85 — down from 1.23 last year — he’s allowing fewer than one base runner per inning.

Soriano hasn’t allowed a hit in his past eight appearances, a stretch that goes back to April 16 and covers 26 batters. Four of those eight appearances have been routine 1-2-3 affairs, and two others have included a walk and a double play, allowing him to face just three hitters. He’s put a man in scoring position once since Tax Day.

The reason for his sudden stinginess is simple. Soriano has recaptured the ability to strike out hitters. Last year, he whiffed a career-low 6.9 batters per nine innings. That’s a number in line with a solid, sinker-balling starter, not a closer. This season, Soriano has struck out 10.4 batters per nine, which would be his best since 2009.

The average velocity of Soriano’s fastball, which he wanted to nudge higher, has actually dropped to 90.6 from 91.5 last season. The key to his strikeouts has been an improved slider. Last year, Soriano threw lifeless sliders, and batters clobbered the pitch so much he essentially abandoned it.

This year, Soriano has recaptured his feel for the slider, and he’s throwing it once every four pitches. It was a liability last year, and now it’s a weapon. The lack of a slider last year turned him into a one-pitch pitcher. Because he can throw his slider again, his fastball is less susceptible, even in its diminished form. His scoreless streak now extends 25 innings, dating from last season.

Soriano is on pace for 57 games finished. If Soriano finishes 62 games this year – a whopping total – he’ll have 120 games finished over the past two seasons. That would trigger a $14 million vesting option for 2015. The Nationals would prefer that doesn’t happen. But if Soriano keeps putting up zeroes and the Nationals keep taking leads into the ninth, they won’t be able to stop him in good faith.

With Doug Fister and Wilson Ramos returning from injuries this week, the Post Sports Live crew debates whether the starting pitcher or catcher will have a bigger impact on the Nationals. (Post Sports Live/The Washington Post)