Overview
Extra innings are additional frames played when the score is tied after nine innings. NPB caps extra innings at 12, declaring a draw if the tie persists, a rule unique to NPB with no MLB equivalent. This draw system carries strategic implications for pennant race standings. Bullpen depth becomes decisive in extra innings: clubs with thin relief corps are disadvantaged, and consecutive extra-inning games late in the season can trigger cascading fatigue effects across the pitching staff. The 2020 COVID-19 season saw NPB adopt nine-inning cutoffs to reduce game duration, while MLB formally introduced the tiebreaker rule (placing a runner on second base to start extra innings) in 2022. NPB has discussed tiebreaker adoption but currently maintains the traditional 12-inning format.