Notice how the angle of the torso rotates up to vertical at the time of impact. The legs catch up to torso at impact. Vertical posture provides the ball lift. As the legs catch up, the torso lifts hard from forward lean to vertical at impact. Combined with the approach pace, this produces power from the consequent leg whip. My observation is that Kickers lose the whip effect and consequent foot speed when they lean too far forward at impact.

For those of you that I have coached in person, this is the diagram of my habit of explaining posture with my hand. You start by leaning forward and then you come up to vertical at the moment of impact.
Hit em straight!
— Coach Crocker —