I think the sharpness of the head, combined with exactly what arteries and veins are cut are really what determines your blood trail.
Good point, it's always been about arrow placement.
So many people are concerned with blowing a hole the size of a baseball through a deer with a huge expandable broadhead, when they should be concerned with where that broadhead is hitting.
I have noticed that when I place a mechanical where it is supposed to be, I don't have to bend over to see the blood trail.
I have also noticed when I place a smaller fixed blade where it is supposed to be I have to bend over to see the blood trail.