I think a factor you must add in is the size of the guy tested. Collins is much thicker than Burnett. Clay is much thicker than Brad Jones. For instance, Allen Iverson would dominate a combine in his prime, but could he have played NFL football at 170lbs.?
What were their weights at their respective combines?
Bud Adams told me the franchise he admired the most was the Kansas City Chiefs. Then he asked for more hookers and blow.