Thank you DXO what a great resource you are!
I'm confused on your statement: A sharpness score of 17 P-Mpix is impressive in terms of the direct competition again ranking 1st for pro standard zooms, ahead of the Nikon 24-70mm with 15 P-Mpix, and Sigma 24-70mm with 16 P-Mpix.
Considering the huge 36-megapixel sensor in the D800 however a sharpness score of 17 P-Mpix is less than half of the camera’s resolution and put into that perspective is less impressive. So whilst the Tamron SP 24-70mm f/2.8 and pro standard zooms in general – offer good features, build and versatility, lenses that cover such a focal range with a large fixed maximum aperture aren't the sharpest.
Are you saying that Tamron is the best of the lot BUT only Prime lens can take advantage of the 36mp sensor? Thanks! Rich