Major League Baseball aimed to create excitement by having the final day of the regular season feature all 15 games starting simultaneously. The intention was fulfilled to a large extent.
While most playoff spots and seeds were settled days earlier, two races drew significant attention on the last day. In the American League West, the Houston Astros and Texas Rangers entered tied with records of 80-81. Meanwhile, the National League’s third wild card spot saw the Philadelphia Phillies and Arizona Diamondbacks competing fiercely.
The Phillies, boasting a 99.1% postseason probability as reported by FanGraphs, managed to secure a spot with a 7-3 victory over the Tampa Bay Rays, avoiding a notorious collapse.
The Astros also made history but of a less flattering kind. Despite winning 9-0 against the already out-of-contention Athletics, they concluded the season with an 81–81 record. This marks the lowest winning percentage for a division winner ever, surpassing the 2005 San Diego Padres’ 82-80 record.
Interestingly, the Astros’ .500 season was a stroke of luck. A team’s run differential, a predictor of future performance, painted a surprising picture. The better a team outperforms their opponents in scoring, the more it predicts future success. Teams frequently exceed or fail to meet these expectations due to factors like injuries, bad luck, or bullpen performance.
Despite the Astros’ negative run differential of -32, translating to an expected record of 78-84, they clinched the division title. The Rangers performed even worse with a -46 differential and a 76-86 expected record.
While conventional wisdom might suggest an early playoffs exit for the Astros, probability tells a different story. The Astros host the White Sox in the wild card series, with FanGraphs giving them a 55% chance to proceed.
Should they succeed, they face the Cleveland Guardians, who finished with a modest +11 run differential and an 85-77 record. The outcome could see the 81-81 Astros reaching the American League Championship Series.
This format intended for last-minute drama delivered but controversially highlighted issues within MLB’s financial incentives and playoff structure. Teams may now aim to perform the minimum required to secure a playoff spot, exemplified by Houston’s performance.