The Pittsburgh Pirates haven't been the most active team this off-season, but during the Winter Meetings, they did make a pair of interesting minor moves worth noting.
First, they acquired left-handed pitcher Andy Oliver from the Detroit Tigers in exchange for catcher Ramon Cabrera. Oliver is a former second-round pick (2009) who, at the time of his selection, Baseball America said "If Oliver can't develop a reliable breaking ball, his fastball velocity and command should make him at worst an effective big league reliever."
After working primarily as a starter in the minors, it appears that even that command is now in question, as Oliver has walked five batters per nine innings in his minor league career. That makes him almost certainly a reliever, but with a questionable breaking ball, it's tough to say how he'll fair against left-handers. Still, he has a power arm that can hit the mid-90's from the left-side, so he'll get his chances.
Cabrera, on the other hand, is a catcher who can do a few things well, but he's 5'8" doesn't have a ton of upside. He doesn't strike out much but doesn't walk much either and has limited offensive potential. He's more of a sure thing to be able to catch in the majors (but not necessarily hit) than Oliver is to be able to pitch in the big leagues, but the Pirates have plenty of catching depth and can afford to part with Cabrera for the shot that Oliver's and his powerful arm figure things out.
In their second move, the Pirates sent pitcher Kyle Kaminska to Boston to compete their acquisition of Zach Stewart. The continued interest in Kaminska is interesting, as the Pirates made a point of acquiring him from the Marlins this past summer, only to see him pitch well in the Arizona Fall League then leave him unprotected in the Rule V draft. He was not selected (not surprising) but then was sent to Boston. Kaminska is a fringe prospect who throws a ton of strikes out is unremarkable at best. The continued interest in him is strange, but the Pirates did manage to turn him into Stewart, who has bounced around and had little success in the majors but does have a decent track record in the minors.
Stewart will almost certainly be a bulpen arm.