What must a pitcher do before changing from the set position to the wind-up position?

The correct answer is that a pitcher must lift his pivot foot backward off the pitcher's plate before changing from the set position to the wind-up position. This action is essential because it signals the transition from a static set position, which is often used for throwing pitches with a potential runner on base, to the more dynamic wind-up position that typically allows for greater momentum and speed in pitching.

In the set position, the pitcher typically keeps one foot on the pitcher's plate and maintains a specific stance aimed at delivering the ball effectively while being in control of any base runners. By lifting the pivot foot backward, the pitcher is indicating readiness to move into the wind-up phase of the pitch, allowing for greater freedom of movement and a full range of motion in the pitch delivery.

Other options involve actions that do not conform to the required mechanics of transitioning between these two positions. For instance, calling "Time" interrupts the game's pace and does not pertain to the proper procedure of changing pitching styles. Putting both hands to the side, rather than maintaining a controlled position, does not correctly represent the transition mechanics either. Additionally, asking for a mound visit does not relate to the dynamics of pitching technique but instead involves the coaching staff and is unrelated to how a pitcher adjusts