Rule sets / OBR / Free Foot Swing
Free Foot Swing
Once the pitcher's free (stride) foot swings past the back edge of the rubber, the pitcher is committed to delivering home. The only exception is a throw to second base on a pickoff play.
If a left-handed or right-handed pitcher swings his free foot past the back edge of the pitcher's rubber, he is required to pitch to the batter except to throw to second base on a pick-off play.
MLB Umpire Development Manual Authoritative interpretation
The pitcher shall be charged with a balk when he:
- Swings any part of his free foot past the back edge of the rubber and throws to first or third base. (Note that this violation is in reference only to the pitcher’s foot. If the knee of the pitcher’s free leg passes behind the back edge of the rubber but his foot does not, he may legally throw to first base or third base with no violation.)