Oliver was 5-1 with a 2.73 ERA in 63 games and 73 innings as a setup reliever for the Angels in 2009 and was 15-3 with a 3.10 ERA for them over the past three seasons. His 3.21 ERA over the past four seasons -- including 2006 with the Mets -- is the 13th best among the 43 left-handed relievers with at least 123 innings pitched over that span.
The Angels have won three straight American League West titles with Oliver as a key member of their bullpen and a leader among their young relievers. He has pitched in 13 postseason games over the past four years.
"D.O. has probably had an impact on a lot of guys in our bullpen, much like Bobby Abreu has on the offensive side," Angels manager Mike Scioscia said during the AL Division Series against the Red Sox. "Darren's been around. He understands his game. He understands coming into situations, what you need to bring out of the bullpen, what you might need to establish focusing a first pitch and making it a good one.
"A lot of things that D.O. does have been important to our younger relief pitchers. I think the biggest impact D.O. has had is the production. If you look at this guy's numbers over the last couple of years, they're terrific. It's something we've really needed, especially with our bullpen in a state of flux. Darren has been as steady as anyone."
Oliver will join a bullpen that currently consists of right-hander Frank Francisco as the closer with C.J. Wilson as the left-handed setup reliever and Darren O'Day, Chris Ray and Neftali Feliz as the right-handed setup relievers.
The Rangers have discussed the possibility of Feliz and/or Wilson moving into the rotation but general manager Jon Daniels said the club's main goal this offseason was to compile as much depth as possible and sort it out in Spring Training.
Manager Ron Washington is hoping to have two left-handed relievers in the bullpen. Eddie Guardado was the Rangers' second left-hander this past season but is now a free agent. The Rangers this winter acquired left-handers Clay Rapada from the Tigers and Ben Snyder from the Orioles, and added rookies Michael Kirkman and Zach Phillips to the 40-man roster.
Oliver, 39, was originally selected by the Rangers in the third round of the 1988 First-Year Player Draft and pitched with them from 1993-98 and again in 2000-01.
He started his career with the Rangers, pitching out of the bullpen in 1993-94. In 1995, the Rangers moved him into the rotation, and he won 14 games in that role during Texas' first AL West-championship season in 1996.
From 1996-2003, he was 78-76 with a 5.14 ERA in 211 Major League starts while making just six appearances as a reliever.
He was 36-27 with a 4.73 ERA in his first 88 starts for the Rangers before being traded to the St. Louis Cardinals on July 31, 1998, along with third baseman Fernando Tatis and outfielder Mark Little for shortstop Royce Clayton and pitcher Todd Stottlemyre.
The Rangers reacquired Oliver as a free agent in 2000, and he went 13-20 with a 6.60 ERA in 49 starts over two years while dealing with some physical issues, including a tired shoulder. At the 2001 Winter Meetings in Boston, Oliver was traded to the Red Sox for outfielder Carl Everett.
His 54 career wins are the second most by a left-handed pitcher in Rangers history behind Kenny Rogers and rank ninth overall.
His last big season as a starter was in 2003, when he went 13-11 with a 5.04 ERA in 32 starts, one relief appearance and 180 1/3 innings with the Rockies. In 2004, he was 3-3 with a 5.94 ERA in 10 starts and 17 relief appearances with the Marlins and Astros, then did not pitch in the big leagues in 2005. Instead he pitched in seven Minor League games in the Rockies' and D-backs' organizations and was let go by both clubs.
The Mets signed him to a Minor League contract and brought him to Spring Training in 2006. He switched to relief full-time and resurrected his career by going 4-1 with a 3.44 ERA in 45 appearances. It was the first time since 1994 that he did not start at least one game in a season and he has made just one start over the past four years.