There is more to it than that though. The gtx 580 for Nvidia is good press. From what I have seen, its getting universally good reviews. A lot more positive than the gtx 480 reviews and in some ways the 5870 reviews(not 5850 which had good reviews). They are not outstanding like say the 5850 reviews, but good none the less.
Fermi gtx 480 had alot of negative press, and AMD took advantage of it. If the 6970 was significantly faster, I don't see why AMD wouldn't release it to rain down on Nv's parade. NV has done it in the past in the form the gtx 7800 512 or even the 5850 ultra. Those were more or less paper launch to help their reputation while a product from the competitor was out and to ruin the hype of the competitors product.
If AMD released the 6970 in little quantities and it out did the gtx 580, 6970 would be priced sky high by street vendors and people wouldn't buy the gtx 580 because it wouldn't be the fastest single chip card anymore. And even the cards they did sell, NV would need to do price drops and it would hurt their margins.
When 6970 began shipping and pricing came down, it would all of a sudden seem like a great value even if it just sold at MSRP, similar to the initial pricing of the 5850.
There would simply be no harm to releasing to reviewers details of the 6970 or review samples.
One more thing is this somewhat contradicts AMD marketing strategies with other products.
AMD is currently giving performance figures for ontario chips and the chips are not going to be released for a couple months or so.
If AMD was really worried about giving competitors knowledge of their products, why show Ontario now, when intel is 10x times more capable of countering their products?
I agree Saaya, AMD should really hire a new marketing department if the 6970 was a super beast.
Doesn't mean the 6970 can't be a monster, it's just boggling that AMD would not give some more hints about performance to quench NV momentum.
One more things I noticed is that the early possible cayman leaks for Vantage xtreme score stopped showing up after NV released a higher score from their card. We were getting regular performance leaks before that.
I don't see why their would be leaks with vantage score 3 months ago, but now every thing has dried up like a desert.