Study: NBA Scorekeepers Pose Potential Integrity Risk In Official Data

Posted on October 12, 2020 - Last Updated on October 9, 2020

A recent academic study flags official NBA scorekeepers as a potential integrity risk in the burgeoning legal sports betting market nationwide.

The study, published last month in the Journal of Prediction Markets, found that that some official scorekeepers are “skewing the statistics” in various venues around the league.

“[I]naccurate official statistics may trigger series ramifications throughout the league,” wrote George Diemer, Jun Woo Kim, and Meredith Kneavel, the paper’s authors. 

The new research study represents the latest probe into how box score-type statistics coming from a single source could impact the sports betting market.

Motivation for new paper

The new paper was motivated in part by Tommy Craggs’s 2009 Deadspin exposé entitled “Confessions of an NBA Scorekeeper” and the accompanying incentives that shape how subjective statistics such as rebounds, assists, and blocks are recorded.

The authors focused on rebounds given Craggs’s suggestion (following an interview with an anonymous NBA scorekeeper) that there are abnormal “home-road rebounding splits.”

To investigate, the researchers gathered game-by-game data from 2000 to 2018 for every team and looked at each team’s top two rebounders every season.  The authors’ final sample included 72,399 NBA games.

Finding rebounds to be a subjective metric, they wrote that “[p]ressure to skew these statistics may come from players, agents, coaches, franchise owners, or even the league itself.”

Rebounding results

“This paper finds that asymmetric incentives affect scorekeepers’ records,” wrote Diemer, Kim, and Kneavel in the main findings of the new paper.  “These results show that the scorekeepers are pushing the [rebounds per game] into the double digit range (when the players has close to 10 rebounds).”

The authors placed five teams in a “suspicious category:”

  • Chicago Bulls
  • Cleveland Cavaliers
  • Denver Nuggets
  • Los Angeles Clippers
  • Miami Heat

The researchers also included pointed analysis directed at two NBA teams:

  • Dallas Mavericks
  • Memphis Grizzlies

For example, the authors found that “the Mavericks’ scorekeepers in Dallas consistently scored the home team differently than the visiting teams.”  

Diemer, Kim, and Kneavel suggest that all of “these inconsistencies and biases also have monetary implications for fans who participate in in fantasy leagues which rely on daily box score statistics.”  

Prior scorekeeper bias research

The new study follows a related scholarly inquiry published in 2017:

“Since the NBA daily fantasy contest scoring systems…rely exclusively on box score statistics (including assists and blocks), scorekeeper behavior has significant influence on these scores,” wrote Matthew von Bommel and Luke Bornn in their Data Mining and Knowledge Discovery article.  “These inconsistencies can have far-reaching consequences.”

The same authors found scorekeeper biases in college basketball too.

Dan Barbarisi highlighted the same issue outside of basketball in Dueling with Kings, his book detailing the rise of daily fantasy sports.  

“[A]n official scorer could be accused of improperly influencing DFS outcomes on judgment-call events like shots-on-goal, or hits and errors,” wrote Barbarisi.

Concerns over DFS integrity are analogous to those in the context of certain prop bets.

Possible preventative steps with official data

So if biased scorekeepers exist, what can be done?

One executive at a sports betting data company suggested that having multiple scorekeepers at event instead of just one would be a simple robustness check to ensure accuracy.

“The more providers that are at a match, the more reliable the information that is going to be coming from it, since it can be cross-checked and assessed more thoroughly,” said Jake Marsh, an executive at STATS Perform, in comments to ESPN in 2017.

Another executive echoed the same concerns last year.

According to Sportradar’s David Lampitt:

“[T]here is also an integrity benefit to having multiple sources of data. This is simply because having a single source of truth leads to at least two problems: firstly it means there is a single point of failure which can potentially create significant financial risk in the betting market; secondly it can lead to ‘information monopolies’ which stifle competition and innovation in the data business, ultimately leading to consumer harm (through increased cost or lack of choice).”   

In a lengthy LawInSport article, attorney Andrew Nixon pinpointed the issue too: “[T]here are inherent dangers in the market being reliant on a single data feed. For example, from a betting perspective, numerous bookmakers may wish to use more than one data feed, whether as a backup or a cross check.”

Any takeaways here?

Academic research tends to run up against considerable headwinds in the industry.

In the case of sports betting official data, a coalition of sports leagues (including a majority of the losers from the Supreme Court sports betting litigation) are lobbying at the state and federal level in support of new laws that would mandate all real-time official league data be procured only from the leagues themselves or their designees.

“It’s very important to us that there’s a single source of truth in the data,” said NFL executive Christopher Halpin in recent comments to the New York Times.

Other sports leagues including the NBA, PGA Tour, and Major League Baseball have similarly espoused a desire for legislative decrees requiring certain sports betting official data to come from a sole source.  In so doing, such leagues posit that there is an integrity risk in not having a sole provider of data.

With its polar opposite conclusion, this new study will probably not shape policy moving forward.  The authors’ findings, however, are a useful reminder for bettors about how data accuracy can determine the success or failure of certain wagers, especially prop bets about the number of rebounds a certain player grabs in the 2020 NBA Finals.    

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Multiple members of the Legal Sports Report team contributed to this article.

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