They made 3 of 4 Eastern Conference finals between 1983 and 1986, and they were good from about 1981 to 1987.
They were missing a point guard. The early Moncrief teams had Marques Johnson and Junior Bridgeman on the wings, and a past-his-prime Bob Lanier in the post, but the best point guard they had was a mediocre Quinn Buckner. The mid-80's Bucks teams had Terry Cummings in the post, who was really good in his prime, and Pressey and Ricky Pierce on the wings, but were playing Moncrief out of position at point. If they just had an above average point guard they would have made an NBA Finals or two. They also had the bad luck of having their best team, in the 1985-1986 season, run right into a Celtics team that was one of the best of all time.