In 1979, Rothstein signed as a scout for the Atlanta Hawks and was named assistant coach in July 1983.[5] He was signed as an assistant for the Detroit Pistons in 1986 before becoming the first coach in Heat history (1988).[4]
Rothstein coached the Heat for three seasons, never leading them to a winning record. Rothstein became a television commentator for the Pistons as well as for the NBA on NBC all during the 1990-91 season. Detroit eventually hired him as their head coach for a season, but he was eventually fired. In 1993, he was hired as an assistant coach for the Cleveland Cavaliers, where he stayed six seasons. In 2000, he was hired as head coach and general manager for the WNBA's Miami Sol, where he stayed during the franchise's entire existence (2000–2003). In 2003, he was hired by the Indiana Pacers as an assistant coach.[6] Rothstein would eventually return to the Heat as an assistant.
On January 3, 2007, Rothstein was named as the interim head coach of the Miami Heat in place of Pat Riley, who took a leave of absence for knee and hip surgery.[7]