What optimism? That's precisely what the leaks showed and the expected performance.
What's odd is the shear level of denial some of the posters have around here. Half a dozen guys running around hysterically trying to pretend they didn't screw up big time again with everyone thinking their idiots. I'm still laughing at the fact AMD played them so easily.
You mean the post from Tweaktown regarding an industrial source have provided the author some questionable raw benchmark numbers. Last time I checked Civ 6, the GTX 1070 scored 83.8 fps at ultra setting with 8X MSAA on 1440p from a test conducted by TPU. https://www.techpowerup.com/reviews/Performance_Analysis/Civilization_6/4.html
If that is not enough for you, there is also a test conducted by Tweaktown on Battlefield 1 put the 1070 with an avg of 105 fps at ultra setting on 1440p. Of course that is DX 11 number, DX 12 number has an avg of 99 fps. http://www.tweaktown.com/tweakipedia/116/fury-vs-gtx-1070-battlefield-dx11-dx12/index.html
http://www.tweaktown.com/tweakipedia/116/fury-vs-gtx-1070-battlefield-dx11-dx12/index.html
Since I don't know whether DOOM was run under Vulkan or OpenGL, I will concede that RX Vega 56 probably does run better than GTX 1070. And I cannot find any benchmark review on the 1070 with high setting except ultra setting which I can provide if you want me to.
While the analysis from the link I provided is not concrete proof regarding performance comparison between GTX 1070 vs RX Vega 56, it does leave me with a lot of question how the test were conducted since there are contradictory information.