Although Cox played several times at colts level, he was never selected for the New South Wales state team and eventually moved to Western Australia to further his opportunities.
His only matches at state level came during the 1985–86 and 1986–87 seasons, when Western Australia's usual wicket-keeper, Tim Zoehrer, was unavailable due to national selection.
Cox achieved moderate success in both Sheffield Shield and McDonald's Cup matches, but was dropped when after Zoehrer's return.
However, due to a back injury, Cox missed the entire 1973–74 season, instead spending time as an umpire in the local competition.
Seeking opportunities at state level, Cox moved to Western Australia for the 1985–86 season in the hope of gaining selection there.