So this is not "flopping"?
Marshall's curveball is a curveball. The palm is not between the ball and the head. The palm is facing close to second base and the back of the hand close to home plate. The hand/wrist must be in an extremely supinated position for this to be possible. From this supinated position, one would pronate while the arm is accelerating forward. The ball does not "flop" out of the hand like traditional pitchers do. The fingers roll over/off the ball in Marshall's motion. In the traditional motion, the ball rolls over/off the fingers.
The amount of supination needed for Marshall's curveball is very close to what Zito is doing here.
Except of course, Zito is not throwing a pronation curve. His curve "flops" out of his hand.