Since Major League Baseball introduced the best-of-five division series 22 years ago, the winner of the first game has won the series 72% of the time. That rate is only slightly higher than in the next rounds’ seven-game series. The abbreviated length for the MLB postseason’s first round does not significantly alter the series’ outcomes, in reality or in theory.
It does change the way the games are played and, mostly, managed, as the first two games of the National League Division series between the Dodgers and Diamondbacks demonstrated.
Statistics tell us that if Team A would ordinarily beat Team B 55% of the time, Team A would be 59% likely to win a five-game series over Team B.