Alex Brandon/AP Alex Brandon/AP

The Nationals released left-handed pitcher Zach Duke yesterday, five days after they designated him for assignment following a failed conversion from starting pitcher to the bullpen. They have yet to reach a resolution with Henry Rodriguez, whom they designated on the same day as Duke, suggesting they could be working on a trade involving the hard-throwing reliever.

The Nationals signed Duke in early December to a guaranteed contract worth $700,000. Duke had gone 15-5 at Class AAA Syracuse in 2012 and pitched well in a September call-up, convincing the Nationals to bring him back. He began the season as the Nationals’ only left-handed reliever but could not make a successful transition to full-time relief and inconsistent work, putting up an 8.71 ERA over 20 2/3 innings. Left-handed batters hit .448 against him.

Rodriguez had been with the Nationals since prior to the 2011 season, when they dealt Josh Willingham to Oakland for him and minor league outfielder Corey Brown. Rodriguez showed flashes of brilliance, but more often could not control his 100-mph fastball. He tumbled from a brief stint as the team’s closer in 2012 to mop-up work this season.