Tanner Roark (4-4, 2.91 ERA) may not have overwhelming stuff, but he’s giving opposing batters fits. (Mitchell Layton/Getty Images)

On June 7, 2013, Tanner Roark pitched a scoreless inning of relief against the Scranton/Wilkes-Barre Rail Riders. He was deemed unworthy of the rotation at Class AAA Syracuse. He did not have a spot on the Nationals’ 40-man roster, and people still pronounced his last name wrong. He was a 26-year-old who, at various points of his professional career, had been valued as a 25th-round draft pick, fair compensation for decline-phase Cristian Guzman and the first player cut from spring training.

Precisely one year later, Saturday morning in San Diego, Roark woke up at the Washington Nationals’ team hotel near Petco Park. On Friday night, he had thrown eight scoreless innings in a 6-0 win over the San Diego Padres. He struck out a career-high 11, walked none and allowed three hits. He lowered his ERA to 2.91, lowest among Washington’s starters. Most now know his name is pronounced “RO-ark.” He is a 27-year-old who, against every shred of logic and order, has been as good as any Nationals starting pitcher.

“Awesome,” Nationals third baseman Anthony Rendon said.

Roark’s stunning ascendancy continued against the worst offense in the majors, a team Roark had already shut out on three hits at Nationals Park this April. Set aside the opponent, though. From the moment Roark arrived in the majors last August, he has entrenched himself as a potential rotation piece that fell out of the sky.

“He’s been pitching like that for us all year,” Manager Matt Williams said. “Just continues to pound the zone, all of his pitches. Pretty impressive.”

Since the Nationals called him up, Roark has made 26 appearances, 17 of them starts. In 131 innings, Roark owns a 2.34 ERA with 101 strikeouts, 28 walks and just eight home runs allowed. Thirteen of the 17 starts have been quality ones — at least six innings with three runs or less allowed.

From the Nationals’ perspective, Roark is manna from heaven. They control his contractual rights through 2019, and until 2017 they owe him nothing more than the league minimum.

If injury strikes or his magical run ends, they have zero risk. Few assets mean more than cheap, controllable starting pitching, and the Nationals added it from nowhere. They found a winning lottery ticket walking down the street, blindfolded, by accident.

Roark’s peripheral statistics suggest he will face regression. He owns a career 3.49 xFIP, or fielding independent pitching, a predictive metric that aims to project a pitcher’s ERA based on league-average defense and normalized home run-to-flyball ratio.

But Roark’s stuff and precise control suggest he could continue to outperform his xFIP. He does not allow many homers because the late action on his sinker prevents batters from hitting the ball with the barrel. He promotes awkward swings and weak contact.

“When his sinker works, we have a lot of things we can do,” catcher Wilson Ramos said. “We can do everything we want.”

Roark’s 14 swinging strikes Friday night were a career high, and his 11 strikeouts were an aberration. But the start was still emblematic. Throwing mostly two-seamers and change-ups, Roark induced 27 called strikes, second most of any National this year behind only Doug Fister’s 28 against the Texas Rangers.

Roark may not possesses overwhelming stuff, but with a quick delivery and a two-seamer that curls around the corners of the plate, he convinces the opposing hitter to keep the bat on his shoulder. He has thrown first-pitch strikes to 65 percent of the batters he has faced, 19th in the majors. Only six major league pitchers have thrown pitches in the zone with more frequency than Roark. And yet batters have swung at only 44.1 percent of his pitches, 24th fewest in the majors.

“Even in a hitter’s count, he doesn’t give you much,” Padres first baseman Yonder Alonso said. “He’s not on the white part. He lives on the black, and he’s got late life.”

In Bill James’s Game Score — a counting system that awards points for innings and outs and gives demerits for hits, walks and runs — Roark’s start Friday registered an 87. The mark has been exceeded only three times in the Nationals’ brief history — once by Roark himself, in his shutout of the Padres in April.

“I wasn’t trying to make perfect pitches,” Roark said. “I was just throwing it, letting it go. If the hitter sees all the same arm action off the fastball, you get him.”

Roark’s faith in his two-seamer has fueled his rise. But so, too, has the epiphany he experienced in the middle of 2012. After frustration mounted following one rocky start, he met with Class AAA Manager Tony Beasley and front office official Doug Harris, then the Nationals’ farm director. He spilled out all of his frustrations, and he decided from then on he would change. He would trust his sinker. He wouldn’t allow misfortune to derail him. He would take deep breaths and plow forward.

It has carried him all the way to the majors. After the eighth inning ended Friday night, he walked off the mound and bumped fists with coaches in the dugout. “Hell of a job,” defensive coordinator Mark Weidemaier said. There wasn’t much else to say.