 As an NBA rookie in 1981–1982, under Coach Dick Motta in Dallas, Nimphius played in 63 games with 27 starts, as the Mavericks finished 28–54.Mark Aguirre, the number one overall pick in the 1981 NBA draft, Jay Vincent and Rolando Blackman were fellow rookies.In 1982–1983, Dallas finished 38–44, with Nimphius averaging 18 minutes 5.3 points and 5.0 rebounds, shooting 49% in 81 games.