<P> The 1951 through 1953 playoffs changed the division finals into a best - of - five playoff . With only nine league members in 1953--54, the NBA cut its postseason tournament field from eight teams to six (from 1954 through 1966, the period of eight to nine league members). Round robins were played in 1954, uniquely in NBA history--a three - team round robin among the three playoff teams in each division . From 1955 to 1966, the first - place team in each division was idle while its two runners - up faced played a best - of - three . Division finals were expanded to best - of - seven in 1958 and division semifinals to best - of - five in 1961 . </P> <P> With ten league members again for the 1966--67 season, eight teams were again admitted to the tournament, providing a simple three - round knockout (8 - team bracket). A year later, the division semifinals were changed to best - of - seven playoff . Then, in 1975 and 1977, respectively, a fifth and sixth team were added to each Division, necessitating an additional first round of best - of - three series . </P> <P> Finally in 1984, the tournament expanded to its present 16 - team, four - round knockout, and the now - complete set of first - round series were expanded to a best - of - five . In 2003 the first round was changed to also be best - of - seven . (Thus all playoff teams from 2003 to present, same as the two Division champions in 1947 and 1948, continue to play at the close of the regular season without idle team ("bye") and may be certain of four playoff games including two at home .) </P> <P> Beginning with the 2004 season, with the addition of the thirtieth NBA franchise, the Charlotte Bobcats, the NBA realigned its divisions . The result was that each conference would have three divisions of five teams each, and the winner of each division was guaranteed a top - three playoff seed . This would change slightly after the 2005--06 season; while division winners still receive automatic playoff berths, they are guaranteed a top - four seed, as described below . </P>

When did the nba change the first round of playoffs to 7 games