The Nationals have recalled left-hander Felipe Rivero from Class AAA, optioning Matt Grace to Syracuse to address a bullpen that was overworked and ineffective during this weekend's sweep in Cincinnati.
Rivero made his major-league debut April 17 for the Nationals but had to be placed on the disabled list after only one appearance when it was discovered he had gastrointestinal bleeding. Once that serious condition was treated, the 23-year-old was optioned to Syracuse, where he made five appearances, allowing two runs in four innings of work.
The Nationals needed a fresh arm in their bullpen after a rough weekend against the Reds in which the relief corps collectively gave up 14 runs on 19 hits and six walks over 11 2/3 innings. Grace was among the biggest culprits, allowing four runs without retiring a batter during Sunday's loss.
Grace impressed upon making his MLB debut, taking the roster spot that opened when Rivero went on the DL, with eight consecutive scoreless appearances to begin his career. He had labored more recently, though, retiring only two of the last 11 batters he faced.
The Nationals made another minor transaction Monday, acquiring right-hander P.J. Walters from the Dodgers in exchange for cash considerations. Walters, 30, has spent time with five different organizations over the last three years and posted a 4.70 ERA in four starts with Class AAA Oklahoma City this season. He'll report to Syracuse and likely join the Chiefs' rotation.
[MORE NATIONALS: THE NATS HAVE A ROUGH WEEKEND IN CINCINNATI]