"We've had a lot of transparent conversations, tried to figure it out, but, at the end of the day, sometimes things just don't work out, and it didn't come back together for James," said manager Clint Hurdle, by way of explaining the parting of the ways. "[The move was made now] to give him an opportunity to catch on with another team while the Major League season was still on."
Before giving in to the shoulder discomfort, McDonald had gone 2-2 in six starts, allowing 19 earned runs in 29 2/3 innings. Since, in a roaming rehab assignment that had touched down at four different levels of the Pirates' Minor League system, McDonald had posted a 6.55 ERA in 10 games.
"He's pitched healthy, shown that he's back," Hurdle said, "We hope he has an opportunity to reignite his career somewhere else."
Cumpton rejoins the club for the third time after a couple of impressive cameo stints. The 24-year-old right-hander from Georgia is 1-1 in four big league starts -- in the last of which he blanked the Cardinals on three hits for seven innings of the Pirates' doubleheader-sweeping 6-0 victory on July 30 at PNC Park.
"He's shown the ability to pitch up here," said Hurdle.
Cumpton may pull some long-relief shifts, with a spot start also a possibility. Although he threw 92 pitches in a Wednesday start, Saturday was his normal side-throw day, so he could instead work in relief against the Cardinals.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. This story was not subject to the approval of Major League Baseball or its clubs.