Patching up the Spurs' holes: how does DAL do it?

[boutons]

DAL is the leader in 3G% allowed, a 29.5%, vs the Spurs are 26th with 37%.

But DAL is 12th in FG% allowed, while Spurs are first.

How does DAL do so well on the perimeter defense that the Spurs fail so badly at?