Matthews began his career with the San Diego Padres in 1999 and has also played for the Brisbane Bandits of the Australian Baseball League,[1] Chicago Cubs, Pittsburgh Pirates, New York Mets, Baltimore Orioles, Texas Rangers, and Los Angeles Angels of Anaheim.

Team radio announcer Eric Nadel said it was the best catch he's ever seen a Rangers outfielder make in his 26 years with the ballclub.

[4] After his fine performance in 2006, with 19 home runs, 79 RBIs, and 194 hits (including 44 doubles), and respected defensive work in the outfield, he was signed by the Angels to a 5-year contract worth $50 million.

Many baseball writers such as ESPN's Rob Neyer have called it one of the worst contracts of all time, citing that Matthews' prior performance was never good enough to deserve it and that his subsequent drop-off should have been predictable to the Angels.

[7] The Angels had reportedly threatened to void Matthew's five-year, $50 million contract if he did not give a response to the allegations.

[8] If he in fact took human growth hormone (HGH) prior to its addition to Major League Baseball's "banned substances list" in 2005, then he would be "grandfathered in", therefore resulting in no punishment but a stern warning, if anything, never to use HGH or any other substance banned by MLB in an attempt to further enhance his playing abilities.

Matthews was the last hitter of the Angels 2009 season, striking out against Mariano Rivera to end game six of the 2009 American League Championship Series.

After the end of the season, Matthews went public with his desire to be traded to another team in spite of having two years left on his contract.

This organization has other plans, and that's OK."[10] The OC Register's Sam Miller doubted Matthews could find a job with another team, comparing him to other aging player with similar attributes.

'[15] Fangraphs' Matthew Carruth called the trade "close to a wash" while Rob Neyer of ESPN.com said "One might argue that the Mets just gave up something for less than nothing.