Wait, just because the Spurs shooters move means that you can't stay at home on them? It's simple, just keep your hands and eyes on your guy at all times instead of doubling or drifting to the paint. You can move around all you want, when you got OKC defenders shadowing you, it's still not gonna get you open. Bonner, Green, Leonard, Jackson, and Diaw shouldn't be left...let Manu/Timmy/Tony try to beat their respective defenders in PnR or isolation all game.
Don't load up on the strong side, don't try to pack it in the paint. That's how most teams play defense and the spurs kill teams for trying that with their perimter passing and weakside body/ball movement.
The spurs shot 50% from 3 against the Thunder in the regular season...that's their advantage...they're not gonna get far trying to post up on the thunder all game.