There’s nothing like home cookin’.
With a home playoff game, a player sleeps in his own bed instead of a hotel and finds local sex workers instead of prowling the clubs. (Joking… but kind of serious. Looking at you, James Harden.)
No wonder home teams win a higher percentage of games than their road opponents.
What should home court advantage be in the 2021 NBA playoffs? There are two competing factors that affect home advantage:
- an increase due to the playoffs
- a decrease due to smaller crowds because of the pandemic
Due to small sample size, getting an exact value is harder than getting warm water to spontaneously separate into hot and cold. However, we’ll make a best estimate based on the data.
First, let’s look at the increase in home court in the playoffs. In the regular season from 2016 through 2019 (3 seasons), NBA teams had a home court advantage of 2.66 points. In the playoffs during those 3 seasons, the home court jumped to 4.11 points, a 55% increase.
Second, let’s look at the effect of reduced crowd size due to the pandemic. The book Scorecasting looked at the reasons behind home court advantage. The authors found that the impact of crowds on referees is a factor. Reduced crowds during the 2020-21 season should imply a smaller home advantage.
Overall, home teams have scored 0.94 points more than road teams, a figure that includes Toronto’s home games in Tampa Bay. However, it’s important to break this down into games with and without fans.
According to data from Basketball Reference, home court has been 2.18 points in the 503 games with some fans this season. In games with no fans during the 2020-21 season, road teams have scored more points than the home team (-0.13 home court advantage).
Let’s suppose NBA home court is 2 points with limited fans during the regular season. During the playoffs, all teams will allow a limited number of fans. Assuming a 50% increase for the playoffs, this gives 3 points for home court during the playoffs.
We can check this 3 point assumption against the markets. With no major injuries in a series, the difference in the spread between home and road games provides an estimate of home court.
For example, Milwaukee was a 5 point favorite against Miami at home in game 2. The markets have Milwaukee +1 as an underdog for game 3 in Miami. Since the Bucks have swung from a home court advantage to not having it, this shift in point spread should be twice a uniform home court. Hence, this 6 point swing implies a 3 point home court.
Denver was a 2 point favorite over Portland at home in game 2. The shift to a 4 point underdog at Portland in game 3 also implies a 3 point home court.
3 points seems roughly correct for home court in the 2021 NBA playoff.
Data driven betting information
This article originally appeared in The Power Rank’s email newsletter. This free service provides data driven betting information, mostly for American football.
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