Don't shoot me. But if the Spurs really are in the market for a physical center, don't they have to consider Kwame Brown if he's available for the minimum? He likely won't be considering he got $8M (or whatever it was) last season from the Warriors. But since he missed almost the entire season, he might fall through the cracks.
He's pretty damn bad offensively but he's grown into a strong post defender who can protect the rim relatively well.