No way your missing deer due to them moving after seeing muzzle flash. They have no idea what a muzzle flash is and there is no sound until after the bullet hits them. I think this theory is bunk. Your pulling some of the shots or misjudging exactly where you aimed. I shot at a deer 4 times this year and missed it with every shot. It an the 4 deer with it never moved a muscle the entire time. They definitely heard shooting not sure if they saw a muzzle flash but either way they have no concept of what is happening. As it turns out, I was hitting a small spruce branch that was just in front of the muzzle without realizing it. Couldn't see it in the scope. Lesson learned better trimming next time.