The home team has won approximately 53.5% of all MLB regular season games from 2010-2019. In a normal season, the home team has a small but significant edge over an evenly matched opponent. However, the upcoming 2020 season is far from normal. We know home field advantage exists in baseball, but do we know why? Will the abnormal circumstances of 2020 take away home field advantage, not change anything, or something in between? In this article, I analyze multiple theories about the factors that cause home field advantage, some of which will not be present in 2020.

Fans

Let’s start with a common viewpoint: home field advantage is derived from the encouragement of the home players from the fans. This is a defensible stance, as home field advantage has been proven to exist in football, basketball, and other sports that have no uniqueness in stadiums and arenas, unlike baseball.  However, if fans played a big factor, wouldn’t that imply some teams have a greater home field advantage than others? The Dodgers, who averaged about 49,000 fans per home game in 2020, the highest in Major League Baseball, would surely experience a greater home field advantage than the Marlins, who housed just 10,000. I decided to graph every individual season since 2010 for all 30 MLB teams, comparing average attendance to the difference between the team’s home and road win percentage.

As you can see in this scatterplot, there seems to be no true relationship between the two factors. The comparison produces an R-squared value of just 0.03; in other words, just 3% of the variability of Home Win% – Away Win% is explained by attendance. This data is important because it is likely that the entire 2020 season is played without fans in the stands. Since we do not see a correlation between attendance and home field advantage, it is not fair to assume that the lack of fans will significantly change the effect of home field advantage.

Travel

Another potential disadvantage for road teams is travelling. They have to stay in a hotel in a different city, spend multiple hours on a plane or bus, and sometimes travel to a different time zone, while playing against a team in their home stadium. This change of routine may throw guys off, especially younger players. While it is difficult to quantify how much an abnormal routine negatively affects teams, I wondered if there is a relationship between distance and home field advantage. For example, if the Mets have a series on the road against the Phillies, the two hour bus ride to Philadelphia likely doesn’t present a major obstacle. Meanwhile, a series against the Padres requires a long flight across the entire country to an area with a three hour time difference. It seems logical to assume the Mets would be at a greater disadvantage(before factoring in the quality of either team) in San Diego than in Philadelphia. The following graph shows the relationship between the distance travelled by the road team and home team win percentage.