In a close box john carmack said you can double the performance of a gpu compare to PC. So you have the best gpu out against the PS4 at 3.72 tflops[2x 1.86 glfops]. This is from the API software overhead that you do not get on a console.
You're taking what the man said out of context.
Optimization on a closed platform is higher, specially when the generation advances and it starts being outdated; that doesn't mean it does more gflops or is in parity with more powerful hardware, just that lots of the time they start doing stuff in roundabout ways in order to preserve performance; kinda like how Shadow of the Colossus was able to fake HDR on the PS2 or how for example PC games can often waste resources on dynamic shadows whereas if you're really tight on a console and the game allows it you might as well just pre-bake the whole level in order to save resources. Gflops don't increase and doing 1080p won't be any easier to do on a platform with less gigaflops than a PC just because it's a closed platform, it's not suddenly the same because a lot of those tasks rely on power alone.
There's no parity and no equivalency, there's just optimization and perseverance in order to keep up; because if it doesn't and the lead platform is the PC you might as well cancel the console version (which is also a factor since with this in mind a lot of games are done targeting consoles and only then up-built with some extras for PC; doing the oposite would prove to be harder; as a matter of fact if it wasn't for console's, the UE4 tech demo is running on existing hardware as is the square-enix one)
This is where he was commenting on it. He was given 2 choices of dc-xbox or ps2 to xbox.
He said it will be bigger than dc-xbox.
http://www.neogaf.com/forum/showpost.php?p=38277835&postcount=7458
Iherre quoted on beyond3d :
http://forum.beyond3d.com/showthread.php?p=1653789&highlight=lherre#post1653789
They're also saying that Wii U is gonna get it's butt kicked by iPad 4 (when iPad 3 is sitting at a mere 30 Gigaflops)
Not every "developer" or "insider" really knows what he's talking about.
Time will tell the actual difference, because right now we're just saying ~600 is different than 1860; visually (and we've seen that) it's really hard to translate what something looking 2/3 times better looks like; other than it looks better.
There'll be a point when it doesn't really matter, probably not this gen, but doubling or trippling the power certainly doesn't translate into a difference as big as it meant 10 years ago.