Right-hander Stolmy Pimentel went on the 15-day disabled list Saturday after inflammation in his right shoulder forced him out of action.
The Pirates recalled right-hander Jared Hughes from Class AAA Indianapolis to take Pimentel's spot. They also optioned right-hander Brandon Cumpton to Indianapolis and called up Vin Mazzaro, who filled the final vacant spot on the Pirates' 40-man roster.
The moves put eight relief pitchers on the Pirates' active roster, but shed no light on the team's plans for Monday's starting pitcher against the San Francisco Giants.
"Fifth starter's still up in the air," manager Clint Hurdle said.
Pimentel allowed four runs on 10 hits and six walks through 111/3 innings this season, but saw his average fastball velocity drop by 4 mph from last year. He joined Wandy Rodriguez, Jeff Locke and Jason Grilli as Pirates pitchers who hit the DL. Pimentel allowed a walk-off home run to Baltimore Orioles catcher Matt Wieters in the 10th inning of Thursday's game.
Hughes could return despite the fact that he had not spent the requisite 10 days in the minors, after being optioned April 27, because a player on the active roster went on the DL.
The Pirates tried to trade Mazzaro, who was one of four relievers without minor league options in a crowded bullpen at the end of spring training, but found no takers. They designated him for assignment in late March, and he accepted an assignment to Indianapolis after clearing waivers. He had not allowed a run in 102/3 innings with Indianapolis this season.
Cumpton joined the rotation for two starts when Rodriguez went on the DL because of inflammation in his right knee. He allowed six runs in 122/3 innings.
Mazzaro and Hughes joined Mark Melancon, Tony Watson, Justin Wilson, Jeanmar Gomez, Bryan Morris and Casey Sadler in what is now an eight-man bullpen. Mazzaro can pitch multiple innings, helping to fill the long-relief void created by Pimentel's trip to the DL. Hughes had four days off before Saturday's game, Mazzaro one.
Hurdle has said the left-handed Locke is a candidate to start Monday. Locke left his start with Indianapolis Thursday after two innings so the Pirates could line him up for a potential spot start Monday. Rodriguez is eligible to come off the DL Monday and could return to the rotation. He threw long toss Saturday, but Hurdle did not have an update on Rodriguez's knee before speaking with reporters.
Heating up in Class AAA
In Andrew Lambo's past 10 games in Indianapolis, he hit .410 with seven doubles, two home runs and a .452 on-base percentage.
"The bat's become more into play," Hurdle said. "He's ridden a couple balls out of the ballpark, made contact, he's becoming more offensive. He's had a good two weeks."
Marte's big game
With his walk-off home run Friday night, Starling Marte joined Rennie Stennett, Johnny Ray and Freddy Sanchez as the only Pirates since divisional play began in 1969 to have a four-hit game that included a walk-off home run. It was Marte's first walk-off hit.
Bill Brink: email@example.com and on Twitter @BrinkPG.