He was drafted by the Milwaukee Bucks in the second round of the 1982 NBA draft, but opted to play basketball for a year in Bologna, Italy. While overseas, Roberts was traded to the New Jersey Nets on November 12, 1982 for Phil Ford and a second-round draft choice, and from there was traded to the San Antonio Spurs on June 7, 1983 with other players in exchange for coach Stan Albeck. Afterwards, he played his first full NBA season with the Spurs.