The idea is that the performance in the drills should sync up with the eye tests applied to the film. If there is a disconnect, then more work needs to be done.
For example, something as basic as Pryor turning out to be 5'11 instead of 6'2" while posting a less than impressive
34 1/2" vert and a 4.58 forty might cause one to go back and examine more closely what happened when he was defending the bigger and faster college receivers. It might turn out, after all the Combine numbers are in, that he happened to avoid those situations by happenstance or perhaps design.