In the 1980s, NBA teams won about 65% of their home games. Today it’s about 55%, and in the playoffs hosting no longer rescues a weaker team the way it once did.
The long report is split here into eight shorter reads. Start at the top, or jump to the suspect you came for.
- Home Court Advantage Is Fading: the case laid out, how much home court advantage has fallen, and why hosting stopped saving the underdog.
- 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 Mystery on the Glass: the biggest single piece of the decline on the stat sheet is rebounding, and it is the one the data can measure but not explain.
- The Usual Suspects: the prime suspects (travel, crowd size, pace, rest, nearly every rule change), nearly all of them with airtight alibis.
- The Playoffs Are Different (and the Same): home court advantage still swings a single playoff game, but a best-of-7 leaves only about a third of that edge, and the regular season hides an opposite twist.
- The Altitude Holdouts: why Denver and Utah still hold the league’s biggest home edges, and the blowouts that keep growing even as home wins shrink.
- 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 four 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: the wider academic and journalistic landscape, and where this report agrees, disagrees, or fills a gap.
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. The prose is drafted with AI under my direction and verified against the analysis before it ships. Tens of hours of arguing and checking.
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.
Figures as of the 2025-26 season.
Correction, 2026-08-16. An earlier version of The Mystery on the Glass said that as shooting accuracy rose, fewer shots missed, so fewer defensive rebounds were there for anyone to collect, and offered that as a partly arithmetic reason the home team’s defensive-rebound edge shrank. The premise is wrong. What rose is points per shot, because more of the makes are threes; the share of shots that go in went from 49.2% to 47.1%, so it did not rise at all. More shots miss now rather than fewer, about 45 a game per team then against about 47 now, so the pool of rebounds to collect grew. The correction runs against the sentence and in favour of the article’s conclusion: the home team’s rebounding edge faded while there was more to collect, not less, so what is left is behaviour rather than arithmetic. The two figures quoted above are new and carry their own checks; no figure this series had already published moved, and article 4 now says all of this.