Among the flurry of roster moves the Nationals made on Tuesday afternoon was an obvious effort by the front office to correct the bullpen. They designated two struggling relievers for assignment, right-hander Henry Rodriguez and left-hander Zach Duke, and called up left-hander Ian Krol from Class AA Harrisburg to fill one of the spots. Over the weekend, the Nationals called up right-hander Erik Davis, one of the three relievers not bullpen on opening day.

Duke and Rodriguez have been a part of the Nationals relief corps’ early-season struggles. Duke, 30, a former starter, struggled in his transition as a reliever, posting a 8.71 ERA in 20 2/3 innings. Rodriguez, 26, recovered slowly from winter elbow surgery and his command issues still baffled the Nationals, who tried to be patient with him. He punched up a 4.00 ERA in 17 games while walking 16 batters in 18 innings.

“The two guys weren’t performing and Davis came up and showed the propensity to get guys out with stuff,” General Manager Mike Rizzo said. “And Ian Krol in double-A has really shown that he has good stuff and the mental makeup to throw the ball over the plate and good stuff and the ability to get out both right-handers and left-handers made him a real interesting option for us.”

Manager Davey Johnson said he expected Duke and Rodriguez to be picked up by other teams; Duke perhaps as a starter. The Nationals signed Duke to a one-year, $700,000 deal this winter, hoping he could serve as the long left-hander in the bullpen one season after he resurrected his career with the organization in Class AAA Syracuse last year. He struggled and left-handed batters hit .448 off him this season. “His situation was really tough starting to learn how to pitch once every 10 days,” Johnson said. “That’s very difficult.”

Rodriguez, 26, the fire-balling right-hander the Nationals acquired in a 2010 trade with Corey Brown from the Oakland Athletics for Josh Willingham, confounded the Nationals for the better part of three seasons with overwhelming, 100 mile per hour stuff but head-scratching wildness. They held out hope he would correct his command issues and he showed glimpses of it last spring training, early last season and on rare opportunities this season. But, with playoff and World Series hopes, the Nationals couldn’t continue to operate with essentially a six-man bullpen or a liability on the mound when he pitched.

“We thought we could make him an impact type of relief pitcher,” Rizzo said. “It just didn’t work out for us. His stuff is well-documented. You’ve all seen it. On occasion he could dominant a baseball game. We tried to be as patient as we could with him but the situation we’re in now it’s a performance league.”

Rodriguez said he was surprised by the news on Tuesday afternoon and expects the Nationals to place him on waivers. “Gotta push ahead and hope for the best for me,” he said in Spanish. “Part of the experience and keep yourself positive. I’m not the first nor the last that this has happened to.”

Now the Nationals turn to Krol, 22, one of the players acquired in the winter trade for Michael Morse. At Harrisburg, Krol posted a 0.69 ERA in 26 innings with a 4.14 strikeout to walk ratio. Krol, who was picked in the seventh round of the 2009 draft by the Athletics,  was named Oakland’s 2010 minor league pitcher of the year after posting a 10-4 record and 2.80 ERA in A and high-A. Since then, however, he struggled but the Nationals have thought highly of him, especially since he joined the organization.

Davis, 26, is a former starter and a relief pitcher the Nationals can use in multiple innings, if needed. And with left-hander Fernando Abad, 27, in the fold, who has performed well in his six appearances and hasn’t allowed a run since being called up, the Nationals have three relatively new faces in their bullpen.

Hard-throwing right-hander Christian Garcia, too, could be an option in the bullpen’s future. He joined Harrisburg on a rehab assignment last week, recovering from a forearm injury he suffered in spring, and has pitched in two games. Once he builds up more arm strength there, Rizzo said the Nationals would determine his path.