Section 10. For all regular season games but not including playoff games, all extra innings, which are defined as beginning in the 10th inning and each subsequent inning of the game thereafter, will begin with a runner on second base. The runner at second base will be the player in the batting order position previous to the leadoff batter of the inning (or a substitute for that player). By way of example, if the number five hitter in the batting order is due to lead off the 10th inning, the number four player in the batting order (or a pinch-runner for such player) shall begin the inning on second base. Any runner or batter removed from the game for a substitute shall be ineligible to return to the game, as is the case in all circumstances under the Official Playing Rules.
For purposes of calculating earned runs, the runner who begins an inning on second base pursuant to this rule shall be deemed to be a runner who has reached second base because of a fielding error, but no error shall be charged to the opposing team or to any player. The loss in such extra-inning games still counts against the pitcher.