Working without a left-hander in the bullpen for much of the season, the Angels acquired Christiansen in a trade with the Giants on Aug. 30, in exchange for Minor League pitchers Dusty Bergman and Ronnie Ray.
The 36-year-old was 0-0 with a 2.45 ERA in 12 relief appearances this season with the Angels, but was left off the playoff roster in both the American League Division Series against the Yankees and the ALCS with White Sox.
Christiansen went 6-1 with a 5.36 ERA, 15 walks and 17 strikeouts in 56 games for the Giants this season.
Christiansen was originally signed by the Pittsburgh Pirates as a non-drafted free agent in 1991 and played with the Pirates from 1995-2000. He also spent time in St. Louis and has a 27-26 record with a 4.27 ERA and 16 saves in 528 career Major League games.
Mike Scarr is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.