How Often Does the Home Team Win in Professional Baseball?

The 2015 season marked the first time in modern Major League Baseball history that all 15 home teams won their games on a day when all 30 MLB teams were scheduled to play. On 11 August 2015, the winning teams -- all playing at home -- were the Toronto Blue Jays, Tampa Bay Buccaneers, Kansas City Royals, Minnesota Twins, St. Louis Cardinals, Arizona Diamondbacks, San Diego Padres, San Francisco Giants, New York Mets, Chicago Cubs, Chicago White Sox, Cleveland Indians, Miami Marlins, Seattle Mariners, and the Los Angeles Dodgers.

According to the Elias Sports Bureau, something similar happened on 23 May 1914, when the home teams went 12-0. Louis Mittel, a doctoral candidate in statistics at Columbia University, figured the odds of a home team sweep on a night with a full slate of games to be 1 in 32,768. Mittel calculated that this is likely to occur roughly once every 80 years.

Root, root, root for the home team:

• Home teams have gone 11-0 on six occasions, including three times in the 1800s. The most recent occurrence was 16 September 1989.
• The Arizona Diamondbacks and the Tampa Bay Rays joined Major League Baseball in 1998 as expansion teams, bringing the league total to 30 teams.
• In a 2010 study, a University of Rochester social psychologist looked at team sports and individual contests such as golf, tennis and boxing, and found that athletes competing at home tend to win slightly more than 60% of the time.