Critical as this is the place where you will be supporting all the weight that you want to be snatching.
For example, if you want to be snatching 250lbs, you need to and you better be able to support 250obs overhead.
As always, head and eyes straight ahead, big chest tight back, core right, elbows externally rotated (rotated to the ceiling) and you want to stack the bones - you want the barbell (from a vertical perspective) over the wrist, over the elbow, over the shoulder, over the hips, over the knees, over the ankles.
As you can see, bringing the barbell back just an inch - when I provide a little bit of tension, right away the athlete knows this is not strong.
When the bar is brought an inch forward of proper position - the same holds true.
But when the bar is behind the head, and is in a "stacked" position - I provide a lot of force and the athlete supports it with seemingly no effort.
So - get your overhead position correct and lift big weights! =D
Oftentimes this gets blown over but important to establish this before snatching - before even overhead squatting really...
Here I have Noble feel the difference between non-optimal and strong positioning. I do this by bringing the barbell back, and then forward, a little bit and tugging not very hard on the bar so that he can feel that with me not tugging very hard that he is in a compromised position. Then I position the barbell in the optimal/strong position and pull hard on the bar - it's easy for Noble to feel how strong and stable he is with very little effort - even when I'm providing 10x the tension.
So what is a strong position? A strong position is when the barbell is stacked over the bones - the bones being the wrist, the shoulder, the hips, the knees, and the ankles - so that if you were to see the athlete from the side, it would be a straight line from the barbell down the side of the body. This way the skeletal structure of the athlete is supporting the barbell.