The exact process: If a game is tied at the end of play (nine innings for a traditional game and seven innings for a doubleheader game), there will be one inning played under International Tiebreaker (ITB) rules. The ITB rules were used by MLB in 2020, where a runner would begin the inning at second base and each side would be given the chance to take the lead.
After the ITB inning, play will shift to a sudden-death tiebreaker. Here’s the description from the MLB Partner League:
Field managers will meet with umpires with the home manager choosing offense or defense. For the team on offense, the player on the lineup card immediately preceding the batter due up will start on first base. The defensive team will have three outs to prevent the offense from scoring. If the team on offense scores they will win the game, while if the defensive team retires the side without scoring a run, they will win. As with the ITB runner, if the runner placed on first base scores, the run will be unearned.
The rule was first proposed by former Florence field manager Dennis Pelfrey, who currently manages in the San Francisco Giants’ organization. It was refined by a committee of Frontier League managers and administrators, including managers Andy McCauley of Evansville, Quebec’s Pat Scalabrini, and Ottawa’s Bobby Brown.
“While sudden death will not happen every game, we believe when it does it will have the fans on their feet,” commented Kevin Winn, Deputy Commissioner for On-Field Operations, via press release. “Created by a former manager, this initiative received overwhelming support of our current field managers and Rules Committee.”
One big advantage for the new rule: The sudden death rule guarantees that no game will be played beyond 10.5 innings or beyond 8.5 innings for a doubleheader game.
There’s been plenty of tinkering with extra-inning rules in 2020 and 2021, ranging from MLB’s embrace of the ITB rules to the MLB Partner League Pioneer League in 2021 scrapping extra innings and instead launched a head-to-head, “sudden death” home-run duel to settle ties, a move league officials described as being popular with fans.