The Pirates have traded reliever Chris Resop to the Oakland Athletics for minor-league reliever Zach Thornton.
Resop was eligible for arbitration, and the move comes hours before teams had to decide whether to tender contracts to arbitration-eligible players, so it's likely the Pirates simply didn't want to take Resop to arbitration. The trade leaves them with a depleted bullpen, but Resop didn't strike out many batters in 2012, and the bullpen is the easiest area of the team for the Pirates to address in free agency.
Thornton is probably nothing special. He struck out 70 batters in 53.2 innings in the California League, which is terrific, but he was 24, old for the level. In addition, he was a late-round draft pick, and isn't regarded as a top prospect. In the end, the Pirates probably planned to non-tender Resop, and they got a warm body for him rather than letting him go for free.
After trading Resop and designating Jeff Karstens for assignment earlier today, the Pirates still have to make official decisions on six players: Neil Walker, James McDonald, Joel Hanrahan, Garrett Jones, Gaby Sanchez and Charlie Morton. Of those, only Morton is likely to be non-tendered.