He must have picked an excellent copy of the original 100-400 for his comparison. I'd say my version 1 lens is average but the version II lens is excellent. My copy of the new one is much sharper wide open plus the much improved IS and twist zoom is a "must upgrade" if you use this lens a lot.
They tested four copies of each generation 100-400, and averaged the numbers.
....that's why LR results are more reliable than other reviews where probably only one unit is tested.