Correction: In a previous version, this article incorrectly reported that Zach Duke was the only left-handed pitcher on Nationals' roster. He is the only left-handed relief pitcher on the roster. This version has been corrected.

A year ago this month, Zach Duke had reached the lowest depths of his career. The Houston Astros, a team that would go on to lose a major league-worst 107 games last season, cut him the last week of spring training. The left-handed pitcher had allowed 18 runs in 141 / 3 spring innings. He felt uncomfortable on the mound; the arm and delivery that made him an all-star three years prior were gone. Nothing worked. “Is my career at the end?” he asked.

March 27, 2012, the day the Astros released him, Duke searched for help. He called two people he knew in the Washington Nationals organization, a team in search of starting pitching depth. By the next day, he had a minor league deal in place to be a starter at Class AAA Syracuse. He obtained copies of his best season, his rookie year in 2005, and pored over his old mechanics.

Duke saturated his mind with footage of his old delivery and spent off hours working with Syracuse pitching coach Greg Booker. By September, he earned a surprising call-up to the big leagues. This season, Duke, now 29, is slated to serve as the Nationals’ left-handed long reliever and emergency starter. In less than a year, he went from being a castaway of the worst team in baseball to the only left-handed relief pitcher on the major league roster of a World Series contender.

“To get a major league deal, after a whole season in the minor leagues, it’s something I’m very thankful for,” he said.

Duke, listed at 6 feet 1, 205 pounds, knew when he joined the Nationals organization that he would need a stint in the minor leagues before returning to the pressures of the majors. The Nationals told him they would use him as a starter with Syracuse; nothing beyond that was discussed. He moved his wife, Kristin, and 2-year-old daughter, Madison, to central New York with him.

For the first month and a half in Syracuse, Duke worked closely with Booker. Instead of leading with his legs and keeping his upper body back, Duke was throwing his hip out in front when he threw. And instead of keeping his shoulders square toward the plate in his delivery, his front shoulder was drifting toward first base as he wound up. As a result, he lost power, hand speed, arm slot and deception. Once Duke fixed those two big flaws, he felt comfortable again.

“I love him,” Nationals Manager Davey Johnson said recently. “He did a heck of a job last year. He did a great job pitching down below in Syracuse. He’s a big league pitcher. He’s high on my list.”

During one two-week stretch in Syracuse, Duke came home from the stadium and watched film of the 14 starts he made as a rookie for nearly an hour every day. “Trying to find the fountain of youth in video tape,” he said. By the end of May, his old delivery started taking hold. He made 26 starts for Syracuse, logging 1641 / 3 innings — his longest stint in the minors since 2004. He punched up a 3.51 ERA and posted a 15-5 record, leading the International League in wins.

Duke insists he wasn’t thinking about a September call-up to the Nationals after finding his way at Syracuse. The first time he knew it was possible was when Chiefs Manager Tony Beasley told him to pack his bags for Washington. In six innings this spring, Duke has thrown well and smoothly, allowing zero earned runs and four hits.

“It’s rewarding to see a person like him reap the benefits of all the hard work he’s put in and get back to what we believed at one time he could be and will be,” said third base coach Trent Jewett, who managed Duke in the minor leagues of the Pittsburgh Pirates, the organization that drafted him in the 20th round in 2001.

Duke impressed the Nationals in his 132 / 3 innings over the final month of last season, allowing only two runs. Over the winter, the Nationals pursued a handful of left-handed relievers and whiffed. Duke, however, was an easy one-year signing. He felt the Nationals had shown goodwill in offering him an opportunity when little was left, so he wanted to return it — an atypical sign of loyalty in modern sports.

“I didn’t really entertain much else,” he said. “The Nationals said, ‘We’ll give you a guaranteed major league deal,’ and I said, ‘You guys helped me out in my lowest point. I want to stay here and be a part of something special and help this team win.’”