The conventional wisdom is that the NBA regular season has too many games. Teams play worse because they are tired, or injured, or resting their stars so they can be ready to actually play hard in the playoffs.
New research shows that the conventional wisdom is…. probably right. In particular, teams play worse by many measures when they have to play two days in a row. That’s what Max Aicardi and I found in a paper published today, “Running on Empty: How Back-to-Backs Impact Pace and the Four Factors of Basketball Success“:
Teams on the second night of a back-to-back shoot less efficiently (lower eFG%), grab fewer offensive rebounds, and play at a slower pace. On defense, they allow opponents to shoot more efficiently, force fewer turnovers, and give up more free throw attempts and second-chance opportunities. Turnover percentage and offensive free throw rate did not change significantly, consistent with our conceptual framework’s distinction between effort-dependent and execution-dependent metrics. While not every metric changed significantly, the overall pattern is clear: second-night back-to-back scheduling is associated with a measurable decline in team performance
The effect sizes here tend to be small, around 0.5-2%, but they are statistically significant given that we studied over 20,000 games, and practically significant given how close NBA games are.
Max had the idea for this paper and wrote the first draft as a student in my Economics Senior Capstone class in 2025. After he graduated, I joined the paper as a coauthor to get it ready for journals. We share the data and code for the paper here.
Economist Writing Every Day 