Internal note: Ricky and Mike, let’s do a recorded zoom where you are explaining this with video of a big leaguer and a young kid side by side or a big leaguer or something like that:

Definition: Loading pattern in which the pelvis works rearward and the trunk goes forward while maintaining an upright shin angle. This movement loads the posterior chain for later use in the delivery.
Identification: Forward trunk flexion as glute works behind heel with knee above ankle.  (Perspective: Back)

Breakdown: Hip hinge is a fancy way of saying we want to try and “load” our hips. Loading, like a catapult, requires that are back hip tilts downwards and slightly around our posting leg. This position keep our hips nice and closed and sets our lower body in a good position to begin to pick up momentum down the mound. Balance is the fundamental constant in hip hinge. If you can’t balance on your back leg, you will find it nearly impossible to load your hips without drifting forward and losing power. A good way to visualize hip hinge is to think about your hips as a seesaw. When we load, we tilt the seesaw back towards the rubber, which lifts our front hip up, loading the catapult. If your athlete is struggling to get his hips into this position, then more often then not they have a balance issue.