Justin Miller, shown in 2017 with the Angels, has capitalized on his opportunity in Washington in a big way. (Chris Carlson/Associated Press)

NEW YORK — Earlier this season, while he was torching the International League and waiting for his big league call-up, Justin Miller had one of his teammates stand at home plate behind a net as he peppered it with pitches out of his unusual closed-off delivery. He wanted some feedback. He wanted to know whether the deception was there.

“I can’t see the ball,” Miller recalled the teammate saying. “Man, I don’t want to hit against you. That just looks disgusting.”

Turns out, nobody wants to hit against Miller. Not at the Class AAA level, not at the major league level, not at any level. After earning a place on the Washington Nationals with 10 2/3 scoreless innings for Class AAA Syracuse, the right-hander has been even better in the majors. He has, in short, been the best reliever in baseball.

Since his May 26 call-up, Miller has faced 34 hitters in 10 2/3 innings across eight appearances. He has retired 32 of the 34. He has 21 strikeouts. He hasn’t allowed a run. He hasn’t walked a batter. His FIP is -0.84. He didn’t allow an extra-base hit until Wednesday, when New York Yankees first baseman Greg Bird doubled. Miller got the win anyway — his fourth as a National — on his 31st birthday, striking out four batters in 1 2/3 innings at Yankee Stadium.

“I guess I’m in the weeds,” Miller said. “I keep snaking wins.”

Since coming up, Miller ranks first in strikeouts, opponents’ batting average (.059), opponents’ on-base percentage (.059) and opponents’ slugging percentage (.091) among relievers who’ve logged at least 10 innings. The difference between his .063 opponents’ weighted on-base average — a statistic used to measure hitters’ overall offensive value — and the second-lowest figure is larger than the difference between No. 2 and No. 15.

He has given Washington length when needed — he logged three perfect innings in a win over the Braves on June 2 — and put out fires, adding versatility and depth to a bullpen that has posted the second-best ERA (1.87) since he joined it after early struggles.

“Honestly, I don’t know how we got him, but I’m glad he’s here,” Nationals Manager Dave Martinez said. “He’s doing really well. And he fits our needs.”

The Nationals got him thanks to a transformation, a connection and some luck. Miller was unemployed last August, released by the Los Angeles Angels after posting a 5.48 ERA in 38 relief appearances for their Class AAA affiliate. He was once a promising prospect and a reliable major leaguer. He was suddenly facing an uncertain future after stints with four organizations.

He was overweight. His fastball, which touched 100 mph before Tommy John surgery in 2012, couldn’t reach 92 mph. He was at a dead end. He needed to make a change to extend his career so, taking future teammate Brandon Kintzler’s advice, Miller started training at Cressey Sports Performance in Las Vegas. He shed pounds and added flexibility. He fine-tuned his mechanics. He emerged a different pitcher.

Kintzler, who shares the same agent, was with Miller in Las Vegas, and said their agent had the Nationals watch him throw a bullpen. Miller was later scheduled to hold a showcase for other teams, but, according to Kintzler, the Nationals signed him before he could be exposed to the competition.

“They just happened to be at the right place at the right time,” Kintzler said.

The Nationals signed Miller to a minor-league deal without an invitation to big league spring training in January, and kept him in extended spring training until he was assigned to Syracuse on April 23. A month later, he was in the big leagues for the first time since 2016.

“It feels great to be back,” Miller said. “It’s a whole lot better than being in the minors. It’s nice. This clubhouse is probably the most laid-back, close clubhouse I’ve been in. Everybody is just super personable. Not just the players. The staff, everybody. Everybody like, it feels like everybody is like, I would say family.”

Miller said this isn’t the best he’s felt in his career. There was a time when his fastball sat 94-96 mph and reached triple digits a couple times. His fastball velocity now averages 93.9 mph. He complements it with a slider in the mid-80s. But he’s throwing more strikes than ever and his stuff plays better because of the deception he creates by starting with his back nearly completely to the batter, with his left leg out toward third base.

It’s an adjustment he first implemented in junior college, after he hit 87 mph once in high school, and he’s exaggerated it over the years, closing himself off more and more. The goal is to keep his hips closed as long as possible, which he said allows him to generate maximum power. It’s all in the hips.

With that formula, Miller has emerged as the latest diamond-in-the-rough for the Nationals, following in the departed Matt Albers’s footsteps and effectively filling his void. He has been a windfall. He has, as his teammate put it, been disgusting.

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