Jeff Cox after being released by the Kansas City Royals signed with the independent New Westminster Frasers in 1974. After being released in 1975 by the Portland Mavericks, Jeff Cox was signed by the Oakland A's organization.
1978 Cox was playing for the Triple A Vancouver Canadians. The Oakland A's later called up Jeff.
When Jeff retired, he then began managing in the the Minor Leagues. The summer of 2000 found Cox managing the Ottawa Lynx when Manager Felipe Alou called Jeff up to be one of his coaches with the Montreal Expos.
Chicago White Sox in 2009 are the team which employs Jeff as the 3rd base coach at this date.