Do you play at "ALL RESOLUTIONS"?
You should know the lower resolutions are all CPU bound, even moreso with these monster graphics cards.
Let's take some slightly more reasonable examples, and PLEASE keep in mind these were done with beta drivers with lots of kinks left in them, which explains why the "summary" scores are lower than they should be. Yes, I am accusing you of intentionally misleading with your post. Oh and it looks like you can't read either, given that my fanboi comment was clearly as a reply to that PremoGS person.
BF3 1080p, 20% faster:
http://tpucdn.com/reviews/AMD/HD_7970/images/bf3_1920_1200.gif
BF3 2560x1600, 23.7% faster:
http://tpucdn.com/reviews/AMD/HD_7970/images/bf3_2560_1600.gif
Summary, 1080p, 11% faster:
http://tpucdn.com/reviews/AMD/HD_7970/images/perfrel_1920.gif
BF3 2560x1600, 19% faster:
http://tpucdn.com/reviews/AMD/HD_7970/images/perfrel_2560.gif
So yeah, I think 20% faster (on beta drivers) is an upgrade, not a sidegrade. Is it one *I* would personally make from a gtx 580? That's another question entirely, but certainly to call the 7970 an equal to the 580 is misleading at best.