Did the Detroit Pistons have a chance to rectify the great mistake of "the wrong DeJuan"?

According to ESPN reporter Chris Broussard (H/T TDP), the San Antonio Spurs have actively engaged a number of teams, including the Detroit Pistons, as it tries to unload itself of the unhappy DeJuan Blair.

It is unknown what the Spurs are trying to get back in return but whatever they proposed to Detroit was apparently rejected, according to Broussard.

My question is why Dumars would reject such a move. Unless the team is in full tank mode (unlikely) and unless the Spurs were trying to extract Kyle Singler (perhaps) or a first-round draft pick (also unlikely), I don't see what the Spurs could have offered that didn't make perfect sense for Detroit.

Yes, Blair has fallen out of the rotation in San Antonio, but he is still an extremely useful player, especially in an area of glaring weakness for Detroit -- rebounding. And this issue has only been exacerbated since the injury to Andre Drummond.