The NBA Draft has a unique history just like most American professional sports drafts. The NBA Draft is not an exact science, but it has changed its format over the past 65 years to help bring young talent into the league in the most effective manner.
Initially, NBA teams could forfeit their first round picks in the draft in order to select a player from a local market to boost ticket sales to games. One of the most notable player selections using the "territorial" method was Celtics legend Tommy Heinsohn who was from the greater Boston area.
After the 1966 season, the NBA Draft changed to the "coin flip" system. This system featured the teams that finished with the worst record in the two divisions (at that time) of the league flipping a coin to see who would have the number one pick in the draft. Whoever lost would go second. After these first two positions, the rest of the teams would be organized in inverse order based on their records. This system lasted until 1985. The most prominent draft pick in this era was in the 1979 NBA Draft when the Lakers wound up with the number one pick after the mismanagement of the Philadelphia 76ers and the New Orleans Jazz. The Lakers selected Magic Johnson who they paired with Kareem Addul Jabbar. The pair won five NBA titles.
The 1985 NBA Draft was the first draft to feature the basic lottery system that is used today. The lottery featured a slight change in 1987 when it was determined that only the top three draft positions would be determined by lottery and that after those three positions, teams would be organized in inverse order based on their records. Patrick Ewing was selected by the New York Knicks with the number one pick in the 1985 NBA Draft. In 1989, the NBA Draft was decreased from its traditional seven rounds to two rounds.
Since 1989, there have been slight changes in the amount of teams that are able to participate in the lottery based on the amount of expansion teams that have entered the NBA. At current, the teams with the worst fourteen regular season records in the NBA are eligible for the NBA Draft Lottery. The worse a record a team has, the better their odds are to win the lottery because they have more balls with the team name on it entered into the pot. Some of the most notable number one picks under the "modern" draft system instituted in 1985 are Patrick Ewing (1985), David Robinson (1987), Shaquille O'Neal (1992), Chris Webber (1993), Allen Iverson (1996), Tim Duncan (1997), Lebron James (2003) and Dwight Howard (2004).