Great question, I hope you get an answer. My experience is that lenses aren't all 'perfect' they are arguably good, but some sort of 'averaging' analysis would be great, whether that is for different areas of the image or focus distance, or even different units.
The bottom line is that these analyses are good, and permit reasonable inter lens comparisons. On the basis of DxOMark's analysis for the Nikkor 24-85 VR, and a similar analysis of the Nikkor 24-120 f4 VR, there was no reason to go for the far more expensive 24-120. This was particularly the case when I was able to pick up an unopened 24-85 VR for about $900 less than the 24-120 from an individual who bought the D600 package with the free 24-85, and wanted to get some of his original purchase price back.
I'd love to see more detail on the testing procedure, but at some point you need to just move ahead and do the best with what you have and can afford.