Like Chuck said: the last guy on the bench is better than the rest of the world. But I think you're right choppsboy. The guys listed aren't very "good". I would say Reggie Evans was leading the league in rebounds last season at Toronto.
I think Grizzly has it right, part of it is talent and part of it is the system that the player is put in. For example, Fabricio Oberto or... Matt Bonner, both those guys would be pine riders for most other teams. They aren't that talented when you compare them to the best of the league. But, when you have a skilled coach, skilled players, and a good system to incorporate specialists into a cohesive unit, that's when you can get guys like Radmanovich, Darko, or even Kwame (much less Bonnner)and get them to play well.
So, basically, we aren't going to acquire a Tyson Chandler from the "trash heap" and turn our system around. But, the Spurs can get a lot more out of "the trash" than other teams. As shown by this team, especially, the only reason our 12th man isn't putting up bigger numbers is because he's not getting time. Still, JJ Hickson would be useful to the Spurs.