ピッチャープレートを踏んだままの二塁への牽制球はボーク？
A pitcher is not required to step off the rubber before throwing to an occupied base in a pick-off attempt. With his foot on the rubber in either the windup position or the "set" position, the pitcher may either: 1) deliver the ball to the batter: 2) throw to a base for a pickoff; or 3) step off the rubber.
no