The Pirates have acquired Clint Robinson and Vin Mazzaro from the Royals in exchange for minor-leaguers Luis Rico and Luis Santos. They've also acquired Zach Stewart from the Red Sox for a player to be named later.
These are minor deals, but it looks like the Pirates acquired a player in Robinson who might have a bit of value, and with the Royals DFAing Robinson last week, the Pirates didn't really give up anything (Rico and Santos hadn't played stateside yet, and aren't regarded as strong prospects). Robinson is a lefty-hitting first baseman who had a good year in Omaha in 2012. He'll be 28 at the start of Spring Training, so he isn't a prospect, but he has always shown a broad base of skills at the plate, and he might be able to help as a bench bat. You may recall that many of us advocated trading for Robinson in about May, when the Pirates' offense was dreadful; that had more to do with the Pirates' offense than with Robinson, but he's still a potentially helpful player. He only plays first, and Garrett Jones, another lefty-hitting first baseman, will almost certainly be back next year, so it will be hard to find playing time for Robinson, but there's no crime in having pinch-hitters who can actually hit. It will be tricky, though -- the Pirates are also pretty likely to continue to carry Gaby Sanchez, and it will be tough to have two bench players who play the same position and have so little versatility.
Mazzaro will likely compete for a role in Spring Training. He's ideally probably someone you'd like to see in the Indianapolis rotation to start the year, although that might not be possible, since he seems to be out of options. He throws relatively hard and has posted good strikeout rates at times, although he's also had control issues. He recently turned 26. It wouldn't be impossible for him to have a decent career as a reliever or perhaps a back-end starter. I would think the Pirates would have him compete for a bullpen role, and I'm sure they won't be afraid to designate him for assignment if he doesn't win one.
Stewart doesn't throw as hard as Mazzaro and doesn't strike out many batters, so he isn't as interesting to me, but his control is better than Mazzaro's. He should be good AAA depth.
UPDATE: The Pirates have designated Matt Hague and Yamaico Navarro for assignment to clear space for Robinson and Mazarro. Robinson looks to be a clear upgrade on Hague, and they play the same position, so there's no need to keep them both, and Hague was clinging for dear life to a roster spot anyway. I think Navarro is still modestly promising, but the DUI probably didn't do him any favors.