You also see why that slightly forward shot in the "Pocket" drops deer so fast.......think back to the many DVD's you have seen. (The latest Truth 4 Bowhunting and Will Primos' very firstkill on the videois a prime example)
All the major high pressure blood vessels to the head lie in that area and if you take them out it's blood pressure GONE to the brain and nighty night.
It's generally a slight "miss" from the point of aim that gives you the biggest margin of error but if you drift that way by accident you'll be climbing down 10 seconds after you shot. LOL