5.07 (e) (8.01(e)) Effect of Removing Pivot Foot From Plate
If the pitcher removes his pivot foot from contact with the pitcher’s plate by stepping backward with that foot, he thereby becomes an infielder and if he makes a wild throw from that position, it shall be considered the same as a wild throw by any other infielder.
Rule 5.07(e) Comment (Rule 8.01(e) Comment):
The pitcher, while off the rubber, may throw to any base. If he makes a wild throw, such throw is the throw of an infielder and what follows is governed by the rules covering a ball thrown by a fielder.