I can think of a couple deer over the years that I shot while their heads were down and made bad hits only to lose them. I know I was always of the frame of mind to try to shoot at them head down if possible with the less chance they see you draw and the idea they are relaxed. Definitely changes my mind just in the physics as they discuss and how a head down deer is already in a better position to drop the body faster and move. Kinda like the track runner as they discussed, try to sprint fast from a standing position vs. down closer to the ground in the starting blocks.