Great thread. I completely agree with most of what has been said already, too many good points have been made to call out each one.
The way I think of it physical action covers just the basics of the hunt and the kill. Perfecting the mental game definitely is what can get you to a higher level. High performing athletes spend a lot of time on that aspect - mental training not just physical. I am not one of those but it seems that is what it takes to become great at any activity, on top of just physical ability. The mental game.
When Magic mentioned about needing a moving target to hit it, I know what he was talking about. I shoot very well on difficult shots. I won't take a difficult shot unless I know I will make it, and when I take it I do make it, its not arrogance its just that simple. The shots I usually mess up are the chip shots, whether with a gun or bow, and that is a result of not focusing like I should. "This is going to be easy" is my worst enemy when I am at full draw on a buck. I have gotten better with that but still have to watch for getting sloppy when things seem "easy" particularly while gun hunting. I try not to even let myself think that word when I am hunting.
The challenge is getting in that mind set, and being able to count on getting in that mindset. I for one think that the harder a person consciously tries to act that out, the less likely they will be to get there. The hunter-killer state of mind is something that happens as a result of focusing on your goal, not as a primary goal itself if that makes any sense.