I don't really agree with your premise on luck as an absolute in that situation. There may be be good fortune or luck, if you will, involved but the Spurs put a decent amount of eval into the guys they've scouted and brought in for workouts. There are certain philosopies that successful organizations adhere to when evaluating players and the Spurs are no different. Player development with successful teams is also a bit different than it is with less successful organizations. If you are talking about ping-pong balls in a lottery hopper..or even certain injuries, pure luck...or good fortune, rules the day. Otherwise, there is more to it than just that.