Complex sentence: The NBA Draft, the annual event in which the 30 franchises in the National Basketball Association select new players for their teams, has distinctive eligibility rules, which have changed several times during the history of the league.
Split into simpler sentences: The NBA Draft is an annual event in which the 30 franchises in the National Basketball Association select new players for their teams. Eligibility rules for prospective players have changed several times during the history of the league.