He played in Major League Baseball (MLB) for the Arizona Diamondbacks, Chicago White Sox and San Diego Padres.

[3] He led his baseball team to two Western League Championships, while setting a record at the school with 28 home runs and 119 RBIs.

[citation needed] Quentin attended Stanford University, where he was named All Pac-10 the three seasons he played (freshman, sophomore and junior).

He finished his Stanford career with a .350 batting average, 35 home runs, 170 RBIs, and 26 stolen bases in 199 games played for the Cardinal.

[9] That season, he led all Arizona minor league players in batting (.332), RBIs (91), runs (103), hits (157), and walks (69), numbers that were divided between Single-A Lancaster and Double-A El Paso.

[10] He also starred on a TV show chronicling the life of a minor leaguer with Chris Young and Dustin Nippert.

[11] Quentin was hitting .290 with 30 doubles, three triples, nine homers and 52 RBI in 85 games for the Tucson Sidewinders[10] when he was called up to the Diamondbacks on July 20, 2006.

After grounding out in his first two major league at bats, Quentin hit a two-run home run off Mark Hendrickson in the sixth inning of Arizona's 5–2 win over the Los Angeles Dodgers.

[14] Quentin began the 2007 season on the disabled list when he was diagnosed with a partial tear of his left labrum during Spring Training.

[15] After producing disappointing results through the first half of the season (.210, five home runs, 28 RBI in 66 games), Quentin was demoted to Triple-A on July 6.

Prior to a game against the Seattle Mariners on August 18, White Sox catcher A. J. Pierzynski said, "As far as I'm concerned, Quentin has been the American League MVP.

Quentin delivered a key eighth-inning grand slam, breaking a 1–1 tie,[21] and kicked off a run that saw the White Sox win 10 of 12 games and charge to first place.

Angels center fielder Torii Hunter characterized his pure power as "tremendous pop, like Hulk Hogan.

[14] Quentin finished fifth in the balloting for AL MVP, behind Dustin Pedroia, Justin Morneau, Kevin Youkilis, and Joe Mauer.

[25] Quentin played well at the start of the 2009 season but he hit a slump after suffering from plantar fasciitis which hampered his swing.

[14][33] Quentin sprained his left shoulder making a diving catch on August 20 and only made two more plate appearances in 2011.

[35] On December 31, 2011, Quentin was traded from the White Sox to his home town San Diego Padres for Simón Castro and Pedro Hernández.

[36] Quentin opened the 2012 season on the disabled list after undergoing arthroscopic surgery on his right knee to repair a torn meniscus in March.

He made his Padres debut on May 28, regularly batting in the clean-up position and playing left field or acting as DH in interleague games.

[39] Quentin played in a total of 86 games and finished the season batting .261/.374/.504 with 16 home runs and 46 RBI in 284 at-bats.

[39] Quentin was still recovering from his knee surgery as the 2013 season began, and he was limited to four games and 14 at-bats in spring training.

On April 11 in a game against the Los Angeles Dodgers, Quentin was hit in the shoulder by a pitch thrown by Zack Greinke.