I don't know how many do this but to compare cameras using DXO I pick a sharp 3rd party lens and look at the sharpness rating on each camera ...
D700 .....11 MP
So you would expect a Canon 5DSR ( a 50MP camera) to be what?? 40MP...no 18 MP
clearly the lens is sharp enough to generate 27MP so why so low ...did Canon fire too soon? (joke)