What I hope you’ll notice is that the arm maintains about the same degree of flexion/bend throughout the release.
The lower arm is pulled down by the upper arm. The upper arm pauses at the torso as the whole unit rotates within the shoulder socket. ***Watch the orientation on the bicep and palm throughout the fastball release. They maintain the almost SAME orientation from 8 o’clock until the fingertips lose contact with the ball. Only then do you see the wrist begin to flex and the forearm pronate into follow through.
Mr. K.B. /\ is spot on!!!