The 7970 launch was problematic because the launch drivers sucked. I said this before but subsequent drivers fixed that issue 2 months later and it was inexcusable - the 7970 was definitely quite a bit faster than the 580 eventually, but the launch drivers sucked - this caused underwhelming launch benchmarks showing 8-10% above the GTX 580. Hell, eyefinity didn't even work correctly IIRC. Later drivers fixed that and improved the performance over the 580 by a ton, but AMD messed the 7970 launch up in many ways.
So yes, the 7970 wasn't represented well at launch (compared to the 580) because of the pathetic driver situation. That issue was rectified later but it should not have happened at all. The bottom line here is that I hope AMD learned lessons from that because the 7970 is how you do NOT launch a GPU. Software is just as important as hardware - if AMD hasn't learned that yet, I feel bad for them. That said, I think they realize their mistakes from that time frame - I do not think they will replicate that situation with the R9 series.
I also agree with Jaydip that nobody really cares about die size. I only care about noise and performance, I believe most feel this way.