structural:expansion
Signaling

The responsibility for selecting the type of pitch is traditionally made by the catcher by relaying hand signals to the pitcher with the fingers. In more advanced play, coaches may give signs to batters and/or runners to initiate special plays in certain situations. A catcher may signal to a position player that they will be trying to throw the runner out. A runner on base may see the pitch sign given by the catcher and hint it to the batter using hand or body motions.