Why is the slice so common?

(Left hand players: in brackets)

80% of amateur golf players produce slice with long irons and woods.

The slice is close related with a head club path outside-inside of the target line.

This cross path from outside to inside is a very common circumstance: For a right-handed (left-handed) player it is more natural to hit the ball – or throw a stone – towards the left (right) side of the body than towards the right (left) side, where the body seems to get in the way and the sensation is more unnatural.

Since the cross club path from outside to inside produces a shot to the left (right), instinctively the clubface is opened so that the trajectory of the ball is in some way compensated.

Another common cause, which tends to be added to the previous one, is the tendency for the wrists on impact not to reach the same position they had during the stance, but somewhat delayed [open]

During the backswing the wrists are rotated clockwise (counter-clockwise) and during downswing they should be rotated the opposite way exactly the same to return to their initial position. Many times this counter twist is minor and the wrists arrive somewhat delayed, causing an clubhead open face at the moment of impact.