The drill one 430 path drill stops the right arm from straightening- allows the body to open and turn- and keeps the golfer pushing force into the ground through the feet and legs. It also sets up the drill three post impact that keeps pressuring the shaft to the finish.
Connection- Power- Force...How do they all tie in? 
The golf club only stays on the target line for a short amount of time. It does however need to enter and exit in a manner that will spit the ball out straight and eliminate curvature. Here is a visual to how it works.
The swing is an arc from an above and inside the ball view. The clubhead should travel along the target line for a few feet before it starts arcing back to the inside. Here is a drill to help achieve that.
Many people talk about Mac Ogrady in awe with regards to his swing and teaching philosophy. It is really no different to what I teach. This video shows him talking about what equates to drill 1- 2 and 3. 
Proper balance and proper ground forces does not ask for the left foot to jump upwards or backwards. This is a sign of a stalling body and is an attempt to try keep the body moving. There is a better way.