The obvious suspect did plenty of damage, but it didn’t solve the whole case. The move to the three-point line accounts for close to half the decline in home court advantage, through shooting, fouls, and turnovers. Home teams also lost almost all of their old advantage on the offensive glass, and the data cannot tell me why.
In the 1980s, NBA teams won about 65% of their home games. Today it’s about 55%. The playoffs fell just as far, from about 68% to 58%, with an earlier fall, a long middle plateau, and a further recent fall.
Outside the pandemic, the crowds didn’t go anywhere: arenas are about as full as they have ever been. Most of the decline shows up in how the game is played. Part of the shrinking turnover edge still has no clear explanation.
The eight short reads below follow each clue. Start at the top, or jump to the suspect you came for.
- Home Court Advantage Is Fading: how far home court advantage has fallen in the regular season and the playoffs, the shape of the fall, and the lineup of suspects.
- The Whistle: the friendly whistle was real in every decade; watch it fade in the regular season, about half from the move to threes and the rest most likely from officiating getting fairer.
- The Three-Point Suspect: the move to the arc is the obvious culprit, so how much of the decline does it actually explain?
- The Glass and the Turnover Gap: two old home edges shrank; the rebounding edge accounts for about 30% of the decline and the turnover edge nearly as much, but much of each is still unexplained.
- The Usual Suspects: travel, crowd size, pace, rest and rule changes, and why each one comes up short.
- The Playoffs Are Different (and the Same): home court advantage still tilts a single playoff game, but a best-of-seven leaves only about a third of that edge, and the favorite’s home edge over the underdog held for decades before shrinking in the latest seasons.
- The Altitude Exception: Denver’s and Utah’s home edges shrank along with everyone else’s, yet they are still the biggest; playoff samples are too small to rank buildings reliably.
- How I Know This Isn’t Made Up: the battery of checks built to break the findings, why most held, and the ones that didn’t.
Want the receipts? The last article, How I Know This Isn’t Made Up, links every check and the full investigation, for anyone who wants to verify a claim rather than take it on faith.
- Why NBA Home Court Advantage Is Disappearing: the big questions answered in one place, if you landed here first.
- Frequently Asked Questions: quick answers to the questions readers ask most, many linking to the article behind them.
- Related Work: academic research and journalism on home court advantage, and where the findings agree or disagree.
About this series.
I’m investigating questions about the NBA that deserve deep dives, and to see what can be understood with some statistical analysis.
Every claim these articles rest on is checked against its own number automatically, and each of those checks has been made to fail on a deliberately wrong one. The numbers are Python on public NBA data anyone can re-pull. I do use AI under my direction and verified against the analysis before it ships.
I’ve done everything I can think of to force it to be correct.
The numbers behind every article are the same public data: every NBA game result since the 1983-84 season, plus NBA.com’s officiating and player-tracking feeds where an article leans on them, all pulled with the open-source nba_api tool; the attendance records come from Basketball-Reference.
Edition history
October 13, 2026 clarification: The summary’s former caption, “Both series slide down across the four decades and neither climbs back,” obscured the playoff plateau. The chart and timing passages now distinguish the earlier fall, middle plateau, and further recent fall; no precise playoff turning year is established.
Figures as of the 2025-26 season.