He played in Major League Baseball (MLB) for the Arizona Diamondbacks and Los Angeles Dodgers.

[1] Trent was impressing critics as he continued to rise through the ranks, batting at .300 with the Double-A affiliate New Britain Rock Cats in 2006 and was picked for the World team in the 2006 All-Star Futures Game.

[2] Following this success, he was promoted to Triple-A in 2007 for the Rochester Red Wings and although struggling in the regular season, he was perhaps the most outstanding individual player in the 2007 Baseball World Cup where he hit at a 523/.580/.614 clip to lead averages, steals (7) and runs (9) and was picked in the Cup All-Star team.

[3] On 6 August 2009, Oeltjen recorded his first major league hit against Pittsburgh Pirates' pitcher Kevin Hart.

He then hit his first major league home run off Pittsburgh Pirates' pitcher Jesse Chavez in the top of the 8th inning, a blast over the right field wall.

[7] He was recalled only 10 days later,[8] and on 10 September as a pinch runner, was the winning run against the Los Angeles Dodgers in a base-on-balls walk-off.

[9] Oeltjen signed a minor league contract which included an invitation to spring training with the Milwaukee Brewers on 4 December 2009.

[10] In 70 games for the Triple-A Nashville Sounds, Oeltjen slashed .301/.355/.496 with eight home runs, 38 RBI, and 13 stolen bases.

[15] He spent the 2013 campaign with the Triple-A Salt Lake Bees, hitting .255/.345/.484 with 14 home runs, 49 RBI, and 21 stolen bases across 99 appearances.

He briefly returned to the Reno Aces, the Diamondbacks' Triple-A affiliate, before being loaned to the Toros de Tijuana of the Mexican Baseball League.

In January 2015, while playing in Australia for the Sydney Blue Sox, he announced his retirement from professional baseball.

[16] During the summer of 2016, Oeltjen briefly joined the Pittsburg Diamonds of the Pacific Association, an independent baseball league.

In July 2016, Oeltjen played for Australia during the 2016 Haarlem Baseball Week, splitting time between right field and DH.