Personally, I think most of you are underrating Ratliff and grossly overrating Mahinmi. However, instead of going off into some long-winded debate, I think I'll just say we'll wait and see. If the Spurs make a trade for another defensive-minded big man, neither Mahinmi nor Ratliff will see the court anyway. If they don't, then we'll have to play with the cards we've been dealt, and I'm willing to bet that Pop will call upon Ratliff more than most people think come April.
I think an experienced defensive player who has consistently averaged between 3.2 and 4.4 blocks per 48 minutes over the past 6 years would be quite the asset for this team. If you're relying on your 3rd to 5th rotation big to score points, when you've already got Parker, Hill, Ginobili, Mason, Jefferson, Duncan, McDyess, Blair, and Bonner/Finley, then you're in trouble either way.