It boils down to if you can have perimeter D from a couple guys and post D from a couple guys-regardless of position you are good.
All the good championship teams had at least a few guys who could matchup on the perimeter and the post:
LA - Perimeter- Kobe, Fisher, Ariza/Artest. Post Shaq/Bynum, Gasol
Det- Perimeter- Chauncey, Rip, Tay. Post- The Wallaces.
Miami- Perimeter- Wade, Payton. Post- Haslem, Shaq, Mourning.
Boston- Perimeter- Rondo, Garnett, Powe. Post- Garnett, Perkins.
SA - Perimeter- Bowen, Finley, Manu. Post- Duncan, various defensive guys...
It is also a huge boost of your defensive players are skilled enough to warrant major minutes without much of a drop off in other areas. Specialists like Bowen could hit the 3, Artest is multifaceted, Powe and Perkins had a nose for rebounding.
I think it is more about having a good perimeter/ post defensive combo then needing defense out of any "position".