The last 3 games, the Spurs have been terrible at getting the 50/50 balls. You could make a pretty good case that getting to the loose balls would have been enough to win the Denver game.
I will admit that they have been playing like they are tired. But they had the ASB to rest, and then they have had a creampuff schedule since. No travel. Days off between all the games. This stretch would be a relative soft spot in a normal season. No - they don't get a pass for being tired right now. But when a team just keeps getting beaten to loose balls? Yeah, something is wrong.