Since the graph is just GFLOPS per watt normalized to Tegra 2, we cannot actually determine the true perf. or the true power consumption from this graph. That said, we can get an estimate of the GFLOPS per watt performance improvement (in the form of a ratio) of Erista vs. Logan vs. older generations of Tegra.
Exactly; however it could still be that Erista doesn't have as many raw GFLOPs after all and bitchslaps all the SoCs it'll succeed by varying degrees but exactly as the slide states.