under 8% arms/chest/delts would have much more definition and vascularity
I have been on stage with people who are absolutely shredded with no real signs of vascularity, as far as separation it concerned that could be due to the fact that he does not have a lot of muscle size and the quality of the picture. You have a point there though.
The one thing that could be fooling me is that his abs are quite tight, thus giving them the illusion of being more defined. Yah more pics would be needed to see how his back looks for a final determination. I have a really good eye but pics are hard and I usually take a percentage off for what the camera adds. These are not great pics for clerity so I think that is a fair assessment.