On the collegiate scene, Roundfield was twice selected to the All-Mid-American Conference Team for Central Michigan University; he was also the 1975 MAC Player of the Year.

Roundfield was selected in the 2nd round of the 1975 NBA draft by the Cleveland Cavaliers, but opted to play for the Indiana Pacers in the last season of the ABA.

[1] In the 1979 NBA Playoffs, Roundfield led the Hawks to a first round win over the Rockets while averaging 18 points, 15 rebounds, and 3.5 blocks a game.

He made the most of his 1980 All-Star appearance debut, scoring 18 points and grabbing 13 rebounds in 27 minutes coming off the bench.

He came close to winning the game's MVP award for his performance, but was overshadowed by fellow Detroit product George Gervin's 34-point output.