He was an assistant coach for all but one year in his tenure, before becoming interim coach in 1991-92 after the departure of Del Harris. His team went 23-42 that year before Mike Dunleavy was named head coach. Hamblen served Milwaukee as an assistant for four further years.
Hamblen was an assistant in the NBA from 1971 until 2011. He coached with the Houston and Denver Rockets, Denver Nuggets, Kansas City and Sacramento Kings, Milwaukee, Chicago Bulls and Los Angeles Lakers.
Hamblen won championships in Chicago and L.A. He was also interim coach of the Lakers in 2004-05, going 10-29.