After spending 1992 in the minors with the Pawtucket Red Sox,[3] he played his final season of baseball in 1993 with the San Diego Padres, the team that originally drafted him.

He managed for the Red Sox from 1995 to 1998 at the Rookie and Class A levels before leaving to join the Oakland Athletics' organization.

He next was named the first-ever manager of the Oakland Athletics' Triple-A affiliate Sacramento River Cats.

In February 2002, Geren led Licey to a second-place finish in the 2002 Caribbean Series held in Caracas, Venezuela.

The 2002 Dominican Republic team included notable MLB players Vladimir Guerrero, Miguel Tejada, and Odalis Perez.

On September 11, 2010, MLB.com announced that Oakland had exercised Geren's option for 2011, assuring him another season in the green and gold.

[11] During his time with the Mets, Geren was praised for his "statistical aptitude" and "strong working knowledge of advanced analytics.

[15] Geren said his decision to leave the Mets for Los Angeles was fueled by a desire to be closer to his family in Southern California.

[19] Geren won his first World Series in the 2020 season, as the Dodgers defeated the Tampa Bay Rays in six games.

[23] Geren's personal life has been featured on several episodes of Spectrum SportsNet LA's television show "Backstage: Dodgers."