Henry Rodriguez has ended his rehab with Class AA Harrisburg and will report to Class AAA Syracuse to continue his progression toward the majors. Rodriguez, the flame-throwing reliever the Nationals acquired from the Oakland A’s by trading Josh Willingham, is on the 15-day disabled after neck spasms threw his mechanics off kilter in spring training.

Rodriguez, 24, came undone because of wildness in three spring training appearances, raising concerns that he had not shed the bugaboo that kept his 100-mph fastball in the minor leagues during most of his career in Oakland. But Rodriguez helped scuttle those issues during three appearances with Harrisburg, when he allowed no runs on three hits, seven strikeouts and, perhaps most significantly, zero walks.

“He’s been throwing the ball well,” Nationals pitching coach Steve McCatty said Wednesday evening. “He’s working on his mechanics, getting that all straightened out. So far, it’s been impressive. But when he gets back [to the majors], we’ll see how these guys react. It’s little bit different pitching here than it is in Harrisburg.”

Rodriguez can continue rehabbing until May 7, 30 days after his stint began, but his promotion to Syracuse today suggests he could join the Nationals bullpen sooner. Rodriguez is out of options, which the Nationals would lose him if they do not promote to the majors when he finishes his rehab assignment.

Last season, Rodriguez allowed 14 earned runs in 27 2/3 innings for Oakland, striking out 33 and allowing 13 walks.