|Texas Rangers — No. 28|
|Born: October 6, 1970|
Kansas City, Missouri
|Bats: Right||Throws: Left|
|September 1, 1993 for the Texas Rangers|
(through 2010 season)
|Earned run average||4.67|
Oliver made his major league debut on September 1, 1993, at the age of 22 at Fenway Park against the Boston Red Sox. In 1996, Oliver became a starter for the Rangers and won 14 games. From 1996 to 1998, Oliver pitched for the Rangers and then was traded to the St. Louis Cardinals for whom he pitched until 1999, returning to the Rangers for the next two years.
In 2002, Oliver pitched for the Boston Red Sox as a left-handed reliever. In 2003, Oliver won 13 games for the Colorado Rockies. In 2004, Oliver pitched for the Florida Marlins and Houston Astros. After 2004, he became a free agent.
In 2005, the Rockies brought him to their spring training camp, but released him. Oliver missed the entire season. After the 2005 season, Oliver signed with the New York Mets and made the team as a reliever. Oliver proved to be very useful in the Mets bullpen, going 4–1 with a 3.44 ERA in 45 games and 81 innings. He made a six-inning relief appearance in Game 3 of the 2006 NLCS. Despite not giving up a run, the Mets lost the game and were down 2–1 in the series. He was mentioned as a potential starter for Game 7; the Mets instead tapped Oliver Perez as the starter.
Oliver became a free agent at the end of the 2006 season. He signed with the Los Angeles Angels of Anaheim, joining Nolan Ryan as the only two players to play for all four original MLB expansion teams (Washington Senators/Texas Rangers, Angels, Mets and Astros). Both Darren and father Bob were also one-time teammates of Ryan: Bob from 1972–74, and Darren in 1993, Ryan's final major league season.
Oliver is the first pitcher ever to pitch in interleague play. He was the starting pitcher in the Texas Rangers' 4–3 loss to the San Francisco Giants on June 12, 1997 at The Ballpark in Arlington.  As a Cardinal, he was also the starting and winning pitcher in the game where Mark McGwire hit his record-tying 61st home run on September 7, 1998.
In 2009, Oliver posted a 5–1 record with a 2.71 ERA. Steve Bisheff of the LA Times called Oliver the "Postseason's Hidden Hero," commenting "The most underrated of all the Angels was their most consistent pitcher in the playoffs." He said the Angels should re-sign him for 2010 despite his age at 39, adding "The Angels would be crazy not to re-sign him." 
However, the Angels did not offer Oliver salary arbitration and they did not agree on terms for his contract.
On December 22, 2009, Oliver signed a one-year $3.5 million contract to return to the Texas Rangers, with a vesting option for 2011 based on the number of games pitched. It is his third stint with the Rangers. On September 15, his 2011 option vested.
Despite pitching with his left-hand, Oliver is extremely effective against right-handed batters. This is largely because of his deceptive delivery and ability to throw sweeping pitches inside to right-handed batters. This has made him particularly effective as a relief pitcher, as he is able to come out and pitch to left-handed batters who struggle against left-handed pitchers and remain in the game to face those who hit from the opposite side of the plate. Further, his endurance gained from years as a starter has allowed him to be a valuable swingman, who can pitch in both traditional short relief as well as for longer periods of time.
Oliver generally throws four pitches. His fastball is heavy and effective and runs between 89 and 92 mph. He also throws two breaking balls, a harder slider that features a modest break but is slow enough to act similarly to a changeup in the eyes of the batter, and a slower curveball that has a larger break.