Jacobs attended Hilltop High School in Chula Vista and Grossmont Junior College in El Cajon, California, before being selected by the New York Mets in the 38th round of the 1999 amateur draft and signed as an infielder.
Over his first four years in the minor leagues, Jacobs developed into a solid power-hitting prospect. In 2003, after a successful year with the AA Binghamton Mets, he won the Sterling Award for top minor league player in the Mets organization. However, in May 2004, while playing for the AAA Norfolk Tides, Jacobs suffered an arm injury and underwent surgery for a torn labrum, which ended his season prematurely. He returned to Binghamton in 2005, continuing his success at the plate. But because of his injury and his mediocre defense as a catcher, Jacobs spent much of the 2005 season learning to play first base.
Jacobs made his major league debut with the Mets on August 21, 2005, hitting a three-run pinch-hit home run against Esteban Loaiza of the Washington Nationals. He went on to hit three more home runs in his next three games, setting an all-time major league record for the most home runs by a player in the first four games of his career.
In only 30 games and 100 at-bats, Jacobs hit a very impressive 11 home runs and 23 RBI. Many people penciled him in as the Mets' first baseman for the 2006 season. However, on November 23, 2005, the Mets traded him and a minor-league pitcher, Yusmeiro Petit, to the Marlins in exchange for Carlos Delgado and $7 million.
Jacobs has been noted for having a nice fluid swing. Although he is primarily a power hitter, Jacobs has shown promise with regard to hitting for average. He also possesses the ability to hit the other way, a rarity for a rookie left-handed hitter.
Jacobs is engaged to be married and resides in Chula Vista during the baseball offseason.
Contrary to popular opinion, Jacobs is not Jewish.
- Selected by New York Mets in the 38th round of the free-agent draft (June 2, 1999 - signed June 25, 1999).
- Traded by New York Mets with Yusmeiro Petit and Grant Psomas to Florida Marlins in exchange for Carlos Delgado and cash (November 24, 2005).
- Jacobs made his major league debut with the New York Mets on August 21, 2005, hitting a three-run pinch-hit home run against Esteban Loaiza of the Washington Nationals. Jacobs went on to hit three more home runs in his next three games, setting an all-time major league record for the most home runs by a player in the first four games of his career.