De La Rosa originally signed as an undrafted amateur free agent on March 20, 1998 with the Arizona Diamondbacks. After two seasons with the Diamondbacks minor league affiliates, he was purchased by the Liga Mexicana de Beisbol (Mexican Baseball League), where he played for the 2000 season.

On February 22, 2001 his contract was again purchased, bringing him back to the United States, playing for the Boston Red Sox affiliates. Still playing in the minors, De La Rosa was traded on November 28, 2003, back to the Arizona Diamondbacks. Just four days later he was traded again, this time to the Milwaukee Brewers.

De La Rosa was called up on August 14, 2004 to make his MLB debut with the Brewers. He continued to split his time between the Brewers and their affiliates, playing in 71 total games over the next two years.

On July 25, 2006, De La Rosa was traded to the Kansas City Royals, where he continued to split his playing time between the majors and the minors. In 2007, his first full season with the Royals, he played in 26 games, finishing the season with a 5.82 ERA.

De La Rosa's role on the Royals for the 2008 season is still yet to be determined, as after their acquisition of Ramon Ramirez on March 26, 2008, De La Rosa was again assigned to the minors.

1. Born: April 5, 1981
2. Birthplace: Monterrey, Nuevo Leon, Mexico
3. Made MLB Debut with the Milwaukee Brewers in 2004