The 26-year-old reliever has made 22 career appearances, 17 of which came with Florida this season. In his 18 innings with the Marlins, Leroux walked 11, allowed 24 hits and gave up 14 earned runs. He struck out 18.
Leroux began the season on the Major League roster, but a right elbow strain landed him on the disabled list in mid-May. When Leroux returned from the injury, he went to the Minors, where he pitched until being called up by the Marlins in early September.
A seventh-round Draft pick in 2005, Leroux had a 6.28 ERA at three Minor League levels this season. The majority of his time was spent with Triple-A New Orleans, where Leroux posted a 6.95 ERA in 21 games. He struck out 20 and walked seven in 22 innings. It was that strikeout rate, as well as Leroux's ability to induce ground balls, that piqued the Pirates' interest.
"He's a big physical right-hander with arm strength," general manager Neal Huntington said of Leroux, whose fastball sits in the low-to-mid 90s. "[He] could be a depth reliever for us, or if he clicks, [he] could be more. We thought it was a pretty reasonable chance to take on a young guy with a good arm and some upside."
Leroux has one option remaining, meaning that the Pirates have some time to see if he can develop into a reliable piece for the big league bullpen.
In order to make room for Leroux on the 40-man roster, the Pirates designated right-hander Brian Bass for assignment. In four appearances with Pittsburgh, Bass allowed 10 earned runs and walked 10 in 7 1/3 innings.
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.