The clubface determines starting direction. The ball will always leave at about right angles to the clubface at separation. Let's think about it in simple terms: the ball rebounds off the clubface and starts in a given direction. How is the ball going to start RIGHT when the clubface is pointing LEFT? There's really no way for the ball to rebound in a direction other than where the face is pointing. In my example, the out-to-in path with an open face will cause the ball to start RIGHT and curve further RIGHT.
We should discuss the fact that the ball is compressed against the face for about 3/4 of an inch down the line of compression during impact. Some will say that this will cause the ball to start in the direction of the clubhead path. I believe that the effect on path in this circumstance is negligible, because as soon as the ball rebounds off the face it's taking off wherever the face is pointing. See 2-D-0 "Directional Factors."
Threaded Mode
