The fault being demonstrated by the lines in this picture is called coming over-the-top. This classic fault is very common with slicers, and is most often characterized by a big looping slice that starts left of the target line (right-handers anyway). This move, of hacking down at the ball from a vertical position with the arms and upper body results in collapsed arms into impact, a loss of power, direction (and most likely big divots). The clubhead gets too far away from the body on the downswing and results in a swing path that travels along the red line, outside of the target line, and then back in. The key to solving this problem is to get the clubhead more behind a player so they can attack the ball from a shallower angle.
To help cure this swing fault, our goal is to encourage a flatter approach into the ball.
There’s a reason you tend to hook a ball from a lie with the ball above your feet – use it to your advantage if you’re suffering from an over-the-top slice.