The Pirates haven't gotten anything out of MLB's compensation system since they've traded all their impending Type A/B free agents before they've reached free agency. This year, though, it seems possible that at least one or two of the Pirates impending veteran free agents (Ryan Doumit, Chris Snyder, Paul Maholm) will be kept until the end of the year.
That's because Doumit, Snyder, and Maholm are all currently in standings to be Type A free agents, meaning that if any of them stayed that way through the end of the year in free agency and then walked, the Pirates would get a first- or second-round pick in return from the team that took them, in addition to a compensation-round pick.
Obviously, there's a fair chance that any of these three could lose Type A status. We're only a third of the way through the season.
Jose Veras also sits Type A at the moment, as per the rankings.
The current statuses of Doumit, Maholm, and Snyder make it even tougher to tell if they'll be traded. Keep in mind that all three have a good shot at being Type B free agents if they lose Type A standing.
Remember that some pretty mediocre players have pulled in comp. picks in recent years. Rod Barajas, Gerald Laird, Gregg Zaun, Jason Varitek, and Miguel Olivo have recently qualified as Type B's. Ramon Hernandez and Bengie Molina have been Type A's.
In short, it seems likely that if the Pirates hang onto their catchers and/or Maholm, they'll get picks back, which could be worth more than any prospect packages they'd get in return for them.