I originally posted this as a response to a comment in another thread, but wanted to reproduce it here.
Players on the 2011 or 2012 Pirates, performance in 2012:
Positive impact:
Paul Maholm: 1.9 bWAR in 32 games for the Cubs/Atlanta
Ryan Ludwick: 1.7 bWAR in 125 games for the Reds
Pedro Ciriaco: 1.1 bWAR in 76 games for Boston
Nate McLouth: 0.8 bWAR in 55 games for Baltimore
Jose Veras: 0.5 bWAR in 72 games for Milwaukee
Steve Pearce: 0.2 bWAR in 61 games for Baltimore/Houston/the Yankees
Xavier Paul: 0.2 bWAR in 55 games for the Reds
Ronny Cedeno: 0.3 bWAR in 78 games for the Mets
Drew Sutton: 0.1 bWAR in 18 games for the Rays after leaving/before rejoining Pittsburgh
Negative values:
Matt Diaz: -0.8 bWAR in 51 games for Atlanta
Gorkys Hernandez: -0.7 bWAR in 45 games for the Marlins
Chris Snyder: -0.6 bWAR in 76 games for Houston
Brad Lincoln: -0.3 bWAR in 24 games for Toronto
Lyle Overbay: -0.1 bWAR in 65 games for Arizona/Atlanta
This is all basically anecdotal; I skimmed through the 2011 and 2012 Pirates team pages at BBRef and picked guys I knew went to other teams. Joe Beimel didn't play in 2012, but I'm sure I missed someone.