Just take a look at who Spurs have to play with Duncan in the paint with the mindset that defense is the most important for these players:
- Bonner: From a Ludden article, "when the Detroit Pistons walked onto the floor after a timeout last month against the Spurs, Rasheed Wallace offered this reminder for his teammates: “Just give the ball to whoever Bonner is on.”". I don't think I need to add more.
- Blair: He has a great rookie year but defense isn't his strength. He is very average in that area. And he is very young rookie, playoffs for him won't be easy at all.
- Ratliff: He has been signed to play a Massenbirg/Willis like role. Hoping more from him is quite unrealistic.
- McDyess: He is solid vet but nothing jaw dropping.
Spurs are extremely weak when it comes to defense from their PF/C. They can surely find a player that will help them more in that area than the current Spurs players. I don't see how you could think otherwise.