It is very likely as no gaming part has been released that the current drivers do not utilise Vega's new features. The card benchmarked by Ryan may indeed be running in some form of compatibility mode. It is still too early to test performance and an organization such as PCPer should have had some disclaimer up indicating this.
This is actually the case.
Tiled rasterization not active, primitive shaders need driver update, etc.
We don't know that. It may very well be that "This is Vega - period".
We'll find out at SIGGRAPH I guess.