In Situation O, what makes F1's action legal with R3 at third and R1 at first?

In this situation, F1's action of stopping with his glove at or below his chin is considered legal because it adheres to the regulations regarding the pitching process. The rules specify that a pitcher must come to a legitimate stop in their motion, and keeping the glove at or below the chin helps to establish that the pitcher is not disguising his pitching motions or deceiving the base runners.

This particular position of the glove indicates that the pitcher is preparing for either a legitimate pitch or a throw while maintaining a clear and fair posture. In contrast, actions such as maintaining the glove above the chin or failing to have a clear stop may raise concerns about the legality of the pitch, potentially leading to situations where base runners could be deemed to have been unfairly deceived. Therefore, by positioning his glove properly, F1 ensures compliance with the pitching rules and the integrity of the game.