"We're excited to add Gregg," said Andrew Friedman, Rays executive vice president of baseball operations. "He's got a lot of experience playing in the American League East. He's been a Ray killer the last couple of years. It will be good getting him on our side.
"He's experienced. He works really good at-bats. And he's a professional in many Rays. We were looking to add that kind of experience down the stretch here."
The Rays will make a corresponding move following Friday night's game in Seattle to make room on the active roster. To make room on the 40-man roster, right-handed pitcher John Meloan was designated for assignment.
Zaun, 38, is batting .244 with four home runs, 13 RBIs, 23 runs scored, 27 walks and a .355 on-base percentage in 56 games for Baltimore. The 15-year Major League veteran has spent time with Baltimore (1995-96; 2009), Florida (1996-98), Texas (1999), Kansas City (2000-01), Houston (2002-03), Colorado (2003) and Toronto (2004-08).
Zaun is a career .250 hitter with 82 home runs and 418 RBIs. Over the past five years (2005-09) he has hit 43 home runs, 38 of which have come against right-handed pitchers. He was a member of the 1997 World Champion Marlins.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.