Organization. A great coach is not going to save a terrible organization. Lawrence Frank is the longest tenured coach in Nets history at 5 years and the only former Nets coach who has a head coaching job is Jason Kidd.
Only way to have long term success as a head coach in the NBA is to get a good roster and win early or be a part of a good organization. No matter how ambitious a coach is, it is still a player’s league and success in the NBA depends more on players than on any given coach.