NBA Betting Against the Public 2003-07 Article: Betting Against the Public in the NBA (NBA Data Nov 2003 – June 2007)

The NBA has been one of SportsInsights most consistent sports, achieving a 54% winning percentage since inception.  SIs NBA Square Plays has had winning seasons in each of the four seasons since SportsInsights started publishing Square Plays.  Our data on Public Betting Percentages mirrors the results of our NBA Square Plays, finding value at the “23% level,” as we see below.  The information on this site is for entertainment and educational purposes only. Use of this information in violation of any federal, state, or local laws is prohibited.

NBA Data 2003-2007

The SportsInsights NBA database now includes FOUR complete season’s worth of data.  Here are some notes on the data we used for this article:

  • Data for the past four seasons (November 2003 through June 2007)
  • Includes the regular season and playoffs
  • Excludes pre-season and All-Star Games
  • About 5,100 games.

Betting Against the Public — NBA

We are pleased that increasing our dataset about 33% (from about 3,800 games to 5,100 games) verifies the results we have seen previously.  The increased data strengthens SportsInsights’ view that Betting Against the Public can be an effective way of obtaining value in the NBA Sports Marketplace.  More specifically, if we see less than 23% of the bets on one team, it means that the public might be undervaluing that team.

Table 1: NBA and Betting Against the Public (2003 to 2007)

Betting % Win %
40% 51.0%
35% 50.5%
30% 51.5%
27% 51.0%
25% 51.0%
23% 53.0%
20% 51.0%

SportsInsights’ Square Plays

SportsInsights’ Premium Members have access to our Square Plays.  SportsInsights uses proprietary information and sportsbook contacts to highlight plays that have excessive “Square” action — and thus should yield value by “betting against” the square bettors.  The performance of our Square Plays, often the most “lopsided-bet games” in terms of both number of bets and money bet — has been positive across all major sports.

As we mentioned above, basketball has been one of our most consistent sports in terms of both “Betting Against the Public” and “Square Plays.”  As we updated the statistics this year, we were pleased that performance has been consistently positive across all the major sports — and actually improved for several sports over the past year!  Below is the average performance of our Square Plays — for spread sports.  Note that Square Plays for moneyline sports like baseball has also been positive, on average.

Table 2: SportsInsights Square Plays – Average Performance by Sport (Since Inception)

Sport Square Play Win %
NBA 54.0%
NCAAB 53.5%
NFL 57.0%
NCAAF 56.5%

We hope that you will make SportsInsights THE PLACE to stop for your sports investing information.  Our Members enjoy some of the most innovative sports marketplace information available!


We do not guarantee that the trends and biases we’ve found will continue to exist. It is impossible to predict the future. Any serious academic research in the field of “market efficiencies” recognizes that inefficiencies may disappear over time. Once inefficiencies are discovered, it is only a matter of time before the market corrects itself. We do not guarantee our data is error-free. However, we’ve tried our best to make sure every score and percentage is correct.