What are the variables of throwing a softball?

Answer 1

Size of ball, weight of ball, surface-smoothness of ball.

Moisture in surface covering of ball, hand coverage area of ball.

Smoothness or grippy-ness of hand surface.

Moisture of hand surface. Lubrication amount provided by any sweat on hand, salt content of sweat.

Wind direction and speed, distance thrown, ambient temperature and humidity. Center of gravity of ball.

Movement paths of wrist, elbow and shoulder.

Acceleration of muscle contraction during throw, (time that throw takes until release from hand, with associated accelerations in all muscles involved).

Finger contact with ball during release.

Spin direction and velocity on ball because of finger contact.

Tiny tiny variable on force of gravity due to elevation?

Hmmm. I just realized that maybe a physicist could double this list.

That's a good start. Really, some guys at MIT could do this better.