In the Tim Duncan era, the only player the Spurs developed was Tony Parker. And even with him, the front office gave up on him at 21-years-old and wanted to bring in a replacement. They said Parker didn't practice hard enough. They said Parker didn't want it bad enough. They said Parker didn't have a good work ethic. Luckily, Jason Kidd didn't sign and the Spurs were forced to settle for Parker as their point guard.
Everyone other young player the Spurs have ever signed in the Tim Duncan era has been let go. Devin Brown? Bad work ethic. Stephen Jackson? Wasn't committed enough. Even Malik Rose who gave his heart and soul to the team was shipped out with his work ethic being questioned.