Gallego, 47, played second base, shortstop, and third base over eight seasons with Oakland (1985-91, 1995), helping the A's win three American League pennants (1988-90) and one World Series title (1989). He spent the past four seasons as the third-base coach and infield instructor for the Rockies, who in 2007 established a Major League record for highest fielding percentage at .98925.
"I like a lot of things about him," A's manager Bob Geren said by phone Wednesday afternoon. "I like that he's an experienced third-base coach, he's had a lot of success working with infielders, and he's been part of winning teams here in Oakland."
Gallego, who spent nine years in the Rockies organization, including four as a roving infield instructor, is filling the lone vacancy on Geren's staff for 2009. He joins bench coach Don Wakamatsu, pitching coach Curt Young, hitting coach Ty Van Burkleo, first-base coach Tye Waller and bullpen coach Ron Romanick.
Tony DeFrancesco, who was hired as Oakland's third-base coach last offseason but moved to first base at midseason and replaced at third by Waller, was informed earlier this month that his contract was not being renewed.
Waller will move back to first base next season.
"I told Tye last night," Geren said. "He's fine with that."
Geren said he didn't know Gallego very well personally until the interview process started last week.
"We spent quite a bit of time talking on the phone since then," Geren said, "and I think he's going to be a great fit for this team and this staff. He's an intense guy who knows how to win. I like that, too."
Mychael Urban is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.