Keep in mind that champions have had difficulty attracting free agents, LA until this summer when they got beat got nowhere in free agency as a champion. Players want to be seen as difference makers not coattail riders. As one example, after Utah was eliminated Malone said he didn't want to join the le team.
Spurs fans thought le, Duncan and no taxes would be huge magnets, but 1st option touches, big money and solo spotlight were far more important to O'Neal, big city far more important to Jourmana and so on. San Antonio doesn't represent a great fit for that many FA's. Champs and small city work against you, not for you.