The deal will all be contingent on the players involved passing physicals.
Hanrahan, 31, is clearly the big chip in the deal. He's coming off back-to-back all-star seasons in which he posted a 2.24 ERA overall and converted 76 out of 84 save chances. He also averaged one strikeout an inning over 128 1/3, but struggled with command, walking 50 unintentionally.
Boston wants Hanrahan as insurance for incumbent closer Andrew Bailey, whom they acquired from the Oakland A's last offseason. Hanrahan made $4.1 million in 2012 and will be due a nice raise in arbitration. Bailey, too, is arbitration eligible.
The Pirates will turn to recently re-signed reliever Jason Grilli to fill their closer role. The 36-year-old right-hander served as a setup man for most of the season, posting a 2.91 ERA. He has five career saves in ten seasons.
The centerpiece of the trade coming back to Pittsburgh will be 25-year-old corner outfielder Jerry Sands. He was expected to make a big splash with the Dodgers in 2011 after posting some huge offensive numbers at Triple-A Albuquerque, but failed to live up to the hype in Los Angeles. He was then traded to Boston in August as the player to be named later in the Adrian Gonzalez deal and will now look to take the next step in Pittsburgh.
It's not exactly a huge haul in return for Pittsburgh unless one of the two unnamed players turn out to be a higher valued prospects than expected.