Even the 290/390 has a DX11 CPU batching problem, i know that for a fact as i went from a 290 to a GTX 970 and given that i develop my own games i can see whats going on in the background.
The truth of the matter is Maxwell is far more efficient at batching, the result is Maxwell can push about 70% more drawcalls in DX11 than AMD can.
The reason why its far more pronounced with Fiji than it is with Hawaii-XT at 1080P is because Fiji is a massively more powerful architecture.
This is why you often see a Fiji GPU only a little faster than a Hawaii-XT, at 1080P, at higher resolution like 4K where the power of the GPU is more important than Drawcalls Fiji comes into its own.
As a GPU its actually more powerful than a GTX 980TI, Fiji's problem is the 980TI is able to use more of its rendering power than Fiji can, at least at 1080P in DX11.
Now, the head of the AMD Radeon Group, Raja Koduri, has actually admitted this problem with thier GPU's, and has said they have completely rebuilt the front end of their GPU's for Polaris to fix this problem.