Ok, the leg lift isn’t only for “Show.” There is a lot of momentum that can be generated by the leg lift which transfers into velocity. The question is, “How come pitchers who have big leg lift’s in the wind up, when pitching in the stretch, have a lower leg lift but still throw the same velocity?” The answer is called the “Load.”
“Loading” is when the pitcher holds his weight back over his back leg, while his front side continues building momentum towards the target. This is why strong legs and core, produce powerful pitching. Look at Eric Gagne in this picture. He is squatting on his back leg, waiting for the perfect time to fire his hips and then his shoulders.
A component of velocity is produced when torque is generated in the two rotational pivots. The rotation of the hips to the rotation of the shoulders. Tim Lincecum calls this the “Rubber Band.” Think of your core as a “Rubber Band.” Rotating the shoulder and hip pivot separate from each other would tighten the “Rubber Band.” This sounds a lot easier than it actually is to perform. This is why a small amount of athletes can throw a baseball over 90 mph.
The importance of the “Load” is that it holds the weight back until the first pivot, the hips, are ready to build maximum torque. Triple extension in the back leg occurs after the “Load” and accelerates momentum into front foot strike, forcing the hips to pivot. If “Separation” occurs between the hips to shoulders then maximum torque is created. Notice the pitcher here in this position. His hip rotation is now complete. He has built maximum torque between his hips and shoulders, you can see this in the tightening of his “Rubber Band,” notice his shirt is stretching like a rubber band would. Now, all that is left to do, is to fire the shoulders forward and then stabilize. Stabilization of the front leg allows the momentum generated from the body to transfer into torque and then into the velocity of the ball.
If the pitcher didn’t “Load” his weight back, as his front side continued to build momentum, optimal hip to shoulder separation would become impossible for the pitcher. His hips and shoulders would move in sync with one another and his chances of reaching his top velocity would be reduced significantly. He would also put more stress on his arm to generate most of his velocity.
In conclusion, a good “Load” position is more valuable for a pitcher than a high lift leg. It generates as much or more momentum but is critical in generating optimal hip to shoulder separation.