Nationals pitcher Aaron Barrett struggled with his control following the 2010 draft, but he’s worked his way back to the point that Washington views him as a potential future closer. (John McDonnell/The Washington Post)

Aaron Barrett laughed as he started to answer the question, an innocuous query for anyone with his job title: Why did he convert from starter to reliever? “Funny story, actually,” Barrett said.

The Washington Nationals selected Barrett in the ninth round of the 2010 draft and shipped him to their rookie class affiliate in Vermont to be a starter. In his first days as a professional, the fundamental skill that defined his job, the act he had done without thought since grade school, abandoned him: He couldn’t throw a baseball from pitching rubber to catcher.

“I kind of lost it, to be honest with you,” Barrett said. “I guess some people call it the yips. Seriously, I literally lost it.”

This winter, almost four years later, Barrett earned a spot on the Nationals’ 40-man roster. He entered his first major league spring training as a long shot at best to crack the opening day roster. But his wicked slider and competitive disposition have made the Nationals believe he could be a midsummer bullpen reinforcement this year and, in the future, a candidate to become their closer.

As Barrett nears the majors, he embraces the blip that threatened his career just as it began. The sudden loss of simple mechanics — the yips, the Thing, Steve Blass disease — has enveloped pitchers and swallowed them whole. Even the ones who survive typically refuse to discuss it, lest they tempt a return. On Saturday afternoon, Barrett talked about his flirtation with sudden, extreme wildness not with fear it might resurface but with pride he has conquered it.

“If you can’t talk about it,” he said, “you’re not over it.”

Barrett has left no doubt he is over it. On Saturday afternoon on Field 3, he strode to the mound for live batting practice and faced a group of hitters that included Bryce Harper. To Harper, Barrett’s mid-90s, four-seam fastball seemed to be scraping 100 mph.

Hitters managed weak contact until an air horn’s blare ended the drill. “Awesome,” minor league pitching coach Paul Menhart told Barrett. “Awesome, awesome, awesome.”

Last season, at age 25, Barrett seized the closer role at Class AA Harrisburg and saved 26 games. He posted a 2.15 ERA and piled up 69 strikeouts in 501 / 3 innings. His slider, a pitch he learned at 16 and immediately became his out pitch, has gained notice within the organization.

“Big league slider,” bench coach Randy Knorr said.

“He’s going to pitch in the big leagues,” Nationals front office official Bob Boone said.

What’s amazing about that: Upon entry into professional baseball, Barrett could not pitch at all. He had been a starting pitcher in college at Mississippi, and the Nationals wanted to evaluate him in that role. “He was a really aggressive kid,” said Jeff Garber, then Vermont’s manager. “He was just throwing the ball too hard, trying to impress.”

In the bullpen one day between starts, one of Barrett’s overthrown pitches veered several feet from the catcher. “As soon as it happened, he tried throwing harder,” Garber said. “And the balls were going everywhere.”

Barrett’s mechanics deteriorated first. His confidence followed. When Barrett threw in the bullpen, fellow relievers stood up from a bench next to the fence and huddled in the corner behind him. Garber tried at first to let Barrett work his issues out during games; Barrett threw nine wild pitches and walked 22 hitters in 21 innings.

“I got booed one outing in Vermont because I threw eight wild pitches to the backstop,” Barrett said. “I remember someone screaming at me, ‘You play professional baseball?’ I mean, it’s embarrassing. I can’t describe it. It just happened. I just lost feel for everything. You see it happen, and it’s scary.”

Garber, now the Nationals’ minor league infield coordinator, sidelined Barrett for a month. He and pitching coach Franklin Bravo conceived a series of drills for Barrett. He turned double plays at shortstop and second base so he could feel what it was like to make a different kind of throw, without thinking.

“You can do two things,” Barrett said. “You either overcome it, or you don’t. That was just kind of a breaking point for me. Honestly, it’s helped me ever since, overcoming that.”

He was made a reliever because he could not be trusted with starts. The Nationals sent him back to rookie ball in 2011. He pitched well on some nights, and on others his wildness flared. After one rough night, he marched into Manager Gary Cathcart’s office.

“I was like, ‘That’s the last time you’ll ever see me do that again,’ ” Barrett recalled. “That was it. That was the last that ever happened.”

In 2011, Barrett walked 6.8 batters per nine innings. In 2012, as he moved through Hagerstown and Potomac, he issued just 2.7 walks per nine. He believes his bout with the yips helped stoke his competitiveness and improved his approach on the mound. “He’s got the mentality for [closing], for sure,” Manager Matt Williams said. Barrett thinks it came from his early struggle.

“You’ve thrown a baseball your whole life. And all of a sudden, you can’t anymore,” Barrett said. “Then it starts getting in there. You’ve got to have a ‘screw it’ attitude. I’m going to throw it through the target as hard as I can. That kind of attitude carries into how I pitch — one pitch at a time, I’m coming at you.”

On Saturday, Barrett stared in at major league hitters. He tried not to think about it, to just make his pitch. His new teammates have no idea about what he overcame to reach this point. If they asked, they would know he has a story to tell, to anyone who wants to hear it.