To visualize swing plane, imagine a sheet of glass stretching from your eyes down to the ball. During the swing, the club should travel just inside this glass. I often use the Stik swing aid to illustrate this plane. (You can also stick a pole in the ground.) With the rod mirroring the imaginary sheet of glass, the clubhead should graze the outside of the top end of the rod during the backswing and the inside of the same spot in the downswing (yes). The top picture shows (no) an improper plane, like Gulbis's. Here's another swing-plane drill: Stand in the address position with your buttocks touching a wall. Swing back until your hands touch high on the wall, and then swing through until your hands touch the wall again.