Had they not made the midseason trade, Malik Rose would have been the other Spur on the team for all three championships.
Of course, there's a great case to be made that without Nazr Mohammed making the Rasho signing look like one of the few Spurs missteps, there wouldn't be another LOB trophy in San Antonio.
This is just another affirmation that the NBA is a superstar driven league. As long as they build around and compliment Duncan, the Spurs will compete. The same thing happened in Chicago. How many players were around for all six titles? Just two. And we all know who they were.