After collegiate graduation, the three–time NCAA champion went on to defend his US World Team spot against reigning US National champion and eventual '18 World Champion David Taylor at the 2017 US World Team Trials in June. After losing the first match, Cox rallied to defeat Taylor twice in a row despite a knee injury to retain the spot, although controversially due to his excessive sweat and alleged passivity. At the 2017 World Championships, he most notably went on to defeat '12 Junior World Championship runner–up Ahmed Dudarov and Dan Kolov International champion Zbigniew Baranowski before losing to Boris Makojev, coming back and defeating 2010 World Champion Mihail Ganev for bronze.