I guess the point of these benchmarks is to show the difference between few things on the screen (low batches) and large number of things on the screen (high batches)
If we look at low batches, we can see there's not much difference between DX11 and DX12. However, once things get busier, the DX11 loses far more FPS than DX12
In my 1080p medium benchmarks, both the DX11 and DX12 versions run at 72fps at "low batch". However, at "high batch" the DX11 version drops by 33fps whereas the DX12 version drops by 21fps.. and I think this is what Microsoft is keen to highlight about DX12
Summary:
DX12 at UHD (4K) - Crazy setting - Difference between low + high: 21% (5fps) Avg: 20.4 fps
DX11 at UHD (4K) - Crazy setting - Difference between low + high: 28% (7fps) Avg: 21.1 fps
DX12 at 1080p - Crazy setting -Difference between low + high: 29% (12fps) Avg: 41.4 fps
DX11 at 1080p - Crazy setting - Difference between low + high: 39% (17fps) Avg: 32.3 fps
DX12 at UHD (4K) - Medium setting - Difference between low + high: 20% (8fps) Avg: 36.7 FPS
DX11 at UHD (4K) - Medium setting - Difference between low + high: 29% (13fps) Avg: 37.5 fps
DX12 at 1080p - Medium setting - Difference between low + high: 28% (21fps) Avg: 60.2 fps
DX11 at 1080p - Medium setting - Difference between low + high: 46% (34fps) Avg: 53.2 FPS
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DX12 at UHD (4K) - Crazy setting - AVG: 20.4 FPS

And then DX12 at 1080p - Crazy setting - AVG: 33.8 FPS

DX11 at UHD (4K) - Crazy setting - AVG: 21.1 FPS

DX11 at 1080p - Crazy setting - AVG: 32.3 FPS

DX12 at UHD (4K) - Medium setting - AVG: 36.7 FPS

DX12 at 1080p - Medium setting - AVG: 60.2 FPS

DX11 at UHD (4K) - Medium setting - AVG: 37.5 FPS

DX11 at 1080p - Medium setting - AVG: 53.2 FPS