When the Oscar "Big O" Robertson joined the Bucks in 1971, he became the key ingredient that led the team to the NBA championship. Oscar Robertson already was an established star when he joined then Lew Alcindor, later Kareem Abdul-Jabbar, to lead the Bucks to the title.
Robertson was the collegiate player of the year three times while leading Cincinnati to the national title. He starred in the 1960 Olympics before starting his NBA career with the Cincinnati Royals. As a rookie, Robertson averaged more than 30 points per game and won Rookie of the Year honors. He became the first player in history to average in triple doubles (30.8 points, 12.5 rebounds, 11.4 assists) in his second year in the league.
With the Bucks, Robertson turned more of a playmaker, feeding Jabbar and scoring only when needed. Robertson also was president of the NBA Players Association and is given credit for helping establish free agency for players.