It's not overly difficult to come up with a comparison as opposed to specific figures for resolution. When a lens is moved away from the sensor, the image circle diameter (at the sensor plane) is increased by virtue of capturing the divergent rays at a greater distance.....just as we do to increase the magnification of a macro lens.
If we take a lens that has a maximum magnification of 0.2x and add enough extension to produce 0.4x at the sensor then we can perform some basic observations to see if the second image has more detail than the first....suitable chart and software to hand. There are other factors coming into play but one can often prove a statement to be right or wrong with the simplest of tests.
I can't offer specifics about the 100-400's (I've never used them) but if they do out-resolve a 5D2/5D3 sensor then they have a far higher resolving power than some of the higher resolving lenses that I own.
Bob