Your body is one connected unit, composed of a variety of different parts, that we want to work in unison, to deliver the ultimate display of power.
Something @nathanstrobel has been using a lot with our throwers (swipe to see), is a series of PVC and bat twirls, where the goal is to learn how to utilize the shoulders in a manner that @davidweck talks about: the coiling core pattern.
Something @javelinanatomy talks a lot about is thinking about the throw as a wave. This can easily be related to Weck’s ideas about the coiling core, and can easily be seen in the Chapman throwing video.
As Chapman’s lead leg reaches peak leg lift (watch closely for the pauses in the video), we also see a forward crunch of the torso. This is “pre-loading” the front half of his body, so that when he moves down the mound, it can provide energy in the opposite direction. We see that energy get utilized as the glove arm gets to its’ peak height and the shoulders have now gone from angled forward to angled back. This seesaw action has now setup Chapman the ability to utilize this energy to snap his torso and throwing arm over his front leg, which we see as he finishes his throw.
By utilizing all 3 planes of motion through the coiling core in the throw, we’ll be able to best utilize our body, and produce maximal throwing velocity as a result.