In which circumstance would a pitcher be ruled legal when using a combination of different pitching stances?

The pitcher is considered legal when using a combination of different pitching stances if they adhere to the rules in either stance. This means that as long as the pitcher complies with the established regulations governing each specific stance—whether they are in a wind-up or set position—they remain in accordance with the rules throughout the pitching motion.

For example, a pitcher might choose to switch between different stances depending on factors like the number of runners on base or the game situation. If they correctly execute each stance according to the rules, such as keeping their pivot foot in contact with the rubber or properly disengaging, they will not be penalized for switching between those stances.

Approval of the stances by the umpire, while sometimes relevant to general legality, does not specifically govern the pitcher's ability to switch stances as long as those stances comply with the rules. Therefore, simply having stances approved or the effect of adjusting gloves does not directly relate to the legality of stance combinations. The core principle is that adherence to the official rules while pitching allows for different stances to be utilized legally.