When you are setting up to the ball one of the key elements (in any swing) is to maintain the correlation between the left arm, the clubhead and the ball position, and realise the effects that this has on the position of the clubface, your grip, and the direction you will be hitting the ball.
Here's a 5 h/cap, who is set up in the classic Y shape... left and right hands meet infront of the crotch and the club sticks straight down.

If you take a line down his left arm then the clubhead is already in front of the ideal impact point (a straight line down the left arm to the ball, allowing for the club to hit the ball on a slight descending trajectory then impact the ground thus taking a divot). You can see quite clearly that if he were to return the club at impact to it's original starting position then there is no way he will take a divot, the club will infact be on the rise. So even before he has swung the club he is going to have to make a compensation in the swing.
If he is unfortunate and does actually return the club to the correct position at impact (yellow line) then he's going to hit a fat shot, some 2 inches behind the ball, so he is going to have to let the club pass his hands (which loses lag and/or makes the clubface point left of the target) or make a compensation to return to the ball correctly, which is INCONSISTANT - ultimately it's a poor setup position and totally avoidable.
At no time during the swing do you want the club head to be infront of the yellow line, well especially not until the ball has been hit and your hands are already halfway round your body on the follow through.
Here's a correct setup position with the left arm and ball correctly positioned...

The club will meet the ball and then continue down into the ground a fraction, taking a divot, whilst the hands power on through the swing. No unnecessary moves are required during the swing however you do need to check your setup!
If you normally set up with a bit of a Y position then changing to the proper straight arm will mean that the clubface and your grip will need adjusting. As you straighten out the angle your clubface will open slightly so you need to square the clubface and remake your grip, also as the hands are pressed forward the same will happen.
The position you are looking for is the clubface in the center of your stance, square, the grip pressed forward slightly and your left hand close to your left trouser pocket.
Here's another image (from the original Stack and Tilt promo vid) that emphasises the position...

As you can see (ignore the lines) the hands are towards the left pocket and the left arm and clubshaft form a straight line which points just behind the ball.
NB: apart from keeping the hands/grip of the club ahead of the clubface at all times, the classic stack and tilt setup suggests that the center of the shoulders and the center of the hips remain directly above the ball as shown below..

It's fairly common to see stack and tilters [sp?] with their centers slightly ahead of the ball as this further encourages an in-to-out swing and a pushdraw flight on the ball. Either is favourable to having your centers behind the ball and hitting it fat!