The Pirates acquired right-handed pitchers Zach Stewart and Vin Mazzaro and first baseman Clint Robinson in a pair of trades with the Boston Red Sox and Kansas City Royals today.
Stewart, 26, has made 33 major league appearances over the past two seasons, going 3-10 with a 6.82 ERA. The Pirates will send a player to be named later to the Red Sox.
In 11 starts for Class AAA Pawtucket last season, Stewart went 3-5 with a 3.94 ERA.
The Pirates traded left-handed pitcher Luis Rico and right-handed pitcher Luis Santos -- both minor leaguers -- to the Royals for Mazzaro and Robinson.
Mazzaro, 26, has a 5.22 ERA in 66 major league appearances and went 4-3 with a 5.73 ERA in 18 appearances, six starts, for the Royals last season.
Robinson, 27, has four major league at-bats and has a career .308 batting average in six minor league seasons.
To make room for Mazzaro and Robinson on the 40-man roster, the Pirates designated infielders Yamaico Navarro and Matt Hague for assignment. Ironically, the Pirates acquired Navarro from the Royals in an offseason trade one year ago.
Rico, 18, finished 2012 pitching in the Dominical Summer League, where he went 0-1 with a 7.04 ERA in 11 appearances, nine of them starts. Santos, 21, also pitched in the Dominican Summer League, posting a 6-3 record and 2.44 ERA in 14 appearances, 12 starts, between two of the Pirates' teams.
Michael Sanserino: firstname.lastname@example.org, 412-263-1722 or on Twitter @msanserino.