Step 2:

Exert force with your triceps concentrically and your biceps eccentrically away from the body

Shoulder Girdle - Both shoulders are in flexion and in abduction as they pronate with downward motion at an aimed target on the ground as they release the ball away from the midline of the body.  Your pectoralis Major and pectoralis Minor are both contracting eccentrically.

Elbow - Elbows are in flexion as the Biceps Brachii are contracting eccentrically and the Triceps Brachii is contracting concentrically but beginning to contract eccentrically as the Bicep Brachii is slowly starting to relax concentrically.

Wrist - Both wrists and fingers are in flexion with the Flexor Digitorum superficialis with the flexor pollicis longus contracting concentrically as they push and release the ball away from the body.  Both wrists are in flexion eccentrically contracting their flexor carpi radialis