The Pirates have shipped pitcher Kyle Kaminska (who they'd previously acquired from the Marlins in the Gaby Sanchez trade) to the Red Sox as the player to be named in the Zach Stewart deal. I assume the Bucs and Red Sox agreed on Kaminska at the time of the deal, but wanted to be sure Kaminska wasn't selected in the Rule 5 Draft. Obviously, the Pirates must not think especially highly of Kaminska (who doesn't have great stuff), even though he pitched pretty well for them, because Stewart probably isn't going anywhere.
This mostly falls into "who cares" territory, at least on a day where there's news. And by "news," I mean Jason Grilli burping, Jason Grilli's agent being Gary Sheffield, the Pirates not taking anyone in the Rule 5 Draft, Neal Huntington's order of a turkey sandwich at lunch probably being really offensive to Pirates fans for some reason ... you know, "news."