Who refs the nba’s referees, the league uses an advanced analytical system to monitor and grade its officials..
By Ben Dowsett
Filed under NBA
Published Feb. 22, 2022
PHOTO ILLUSTRATION BY EMILY SCHERER / GETTY IMAGES
The concept of constant evolution in sports isn’t exclusive to athletes and tactics. It’s central to the men and women who officiate the games as well.
Referee mechanics — where to stand, how to move, who makes which calls — weren’t taught uniformly in the NBA until the early 1980s , over 30 years into the league’s existence. The use of VCRs and videotapes for referee training wouldn’t begin in earnest until a few years later. The NBA didn’t even begin using three officials in its games full-time until 1988 .
As the world around it has modernized, though, so has the NBA. Today’s league officiating department relies more than ever on a well-known sports buzzword: Analytics.
Every single call made by NBA referees — and many of those not made — is graded by impartial observers, then inputted into a vast database including every official in the league. This data is used in ongoing referee training and development, and it helps in determining ref promotions and playoff assignments. Teams are even given partial access to and are allowed to make some inquiries into specific calls.
This is no mom-and-pop setup. It’s a full-fledged operation involving more than two dozen full-time staffers, from former NBA officials to outside consultants and quantitative analysts. It’s also a realm into which the public has had very little window, even as analytics and technology have become larger and larger parts of the league’s officiating department in recent years.
FiveThirtyEight spoke with more than 25 people across the NBA, from league staffers in charge of data collection and use to front-office executives, to understand exactly how this referee-grading and analytics program works.
Many an NBA fan recognizes Secaucus, New Jersey, as home to the league’s Replay Center, but that’s just one small piece of league and referee operations taking place there. Secaucus is also the NBA’s hub for its referee review and grading program, which employs a staff of over 25 people in various roles.
A key figure here is Steven Angel, one of the NBA’s longest-tenured employees at nearly 14 years. Angel was part of a consulting firm that helped redesign the league’s referee data in the early 2000s when David Stern was commissioner; he was eventually brought on full-time as part of the officiating department, now occupying the role of senior vice president of game analytics and strategy.
When Angel started working with the league, the sophistication of referee reviews and grading systems matched the limited technology that was available. Around the turn of the millennium, the NBA started assigning observers to attend games in-person in their geographical area, then return home and break the same game down again via DVR later that night. Angel, with his consulting background, noticed potential problems with training and arena biases, and the system was brought entirely in-house in 2013.
When the NBA brass decided to begin sharing referee game grades and reports with individual franchises in 2015, they quickly realized that many teams were focused on different call and play types than the league’s own referee advisers — understandable given that teams have their own interests at heart, while advisers are focused on leaguewide referee performance. Standardizing these definitions across the board became a major piece of Angel’s department, one that persists to this day under the title of “Rules Clarity Project.”
Those involved work directly with the NBA’s competition committee — which comprises a group of owners, general managers, coaches, referees and players — plus representatives from all 30 teams and the referee’s union. Angel sums up the aim of this project simply: “What actually constitutes an error? The game is one long non-call, except when the whistle is blowing,” Angel told FiveThirtyEight. “Can we agree on what constitutes a foul?”
Angel’s team also handles the realm of integrity. It looks for any and all possible indicators of bias, whether conscious or subconscious. The name “ Donaghy ” is rarely uttered in league circles today, but there’s an obvious desire to protect against even the suggestion of impropriety — especially given the NBA’s own stated interest in the arena of sports gambling.
“We monitor gambling lines in Las Vegas,” Angel said. “We look to see if there’s any indication of manipulation or bias. That is hopefully a big, big waste of time, but we are still diligent in that effort.”
The biggest element Angel oversees, though, is the NBA’s staff of dedicated referee reviewers.
While certain roles in the league’s officiating department are held by former referees, game reviewers are not — again, the goal here is limiting any potential for bias. Rather, Angel and his staff look for “basketball-centric individuals” who have coached or played at some level and have a strong baseline of knowledge but don’t have specific connections with NBA franchises.
In the early years of this program, applicants for game reviewer jobs were given tests on their basketball acumen. Quickly, though, the league realized those tests were asking the wrong questions.
“We believe we can teach what [reviewers] need to look at,” Angel said. “What we need to find in them is the ability to sit and focus for long periods of time.”
Reviewing NBA referees is an arduous, painstaking task. Doing the job correctly might require watching the same three-second play clip over a dozen times at numerous angles. A single game review takes between six and eight hours, per multiple members of the department. Dedication and focus are just as important as actual basketball knowledge.
The interview process today is more focused on these sorts of skills. These are prestigious roles: The NBA’s staff of game reviewers numbers 15 at most, including 10 standard reviewers, three senior reviewers and a couple of specialized roles (such as one reviewer dedicated solely to gambling lines and related integrity concepts).
Game reviewers are trained on three specific components of the job:
- How to grade plays: What constitutes an infraction vs. what doesn’t? Which types of plays need to be included on game reports?
- Which ref is responsible: Reviewers grade whether an infraction took place, but also which referee on the floor was responsible for making (or not making) that call. This involves a detailed knowledge of NBA referee mechanics for each of the three positions an official occupies on the floor ( lead, slot and trail ).
- Use of the Game Review System technology.
The Game Review System, or GRS, is the technological foundation of modern NBA referee grading, one designed in-house and updated several times since the mid-2000s. The goal is to present reviewers with a standardized dashboard they access via computer, with processes that can be applied as evenly as possible to every single NBA game.
Again, there’s major emphasis here on which plays are included. The league could demand reviewers break down every single dribble in each game, labeling “no infraction” each time a player successfully moved without traveling; while that might allow the NBA to claim 99.99 percent accuracy on all call types, it wouldn’t be a feasible use of reviewer time — and the resulting data would be almost useless.
Instead, reviewers get a major assist here from modern technology: Second Spectrum camera tracking, which is present in all 29 NBA arenas, is integrated into GRS. This data is used to “pre-tag” various common events in a basketball game, such as shots, passes, drives, screens and dribble initiations. Instead of manually combing through every second of game action, hemming and hawing on which plays to cover and which to leave alone, reviewers have a standardized shorthand they can lean on.
Generally speaking, reviewers can categorize — or “tag” — a play in one of four ways:
- Infraction: An infraction of NBA rules clearly took place on the play in question.
- No Infraction: An infraction of NBA rules clearly did not take place.
- Potential Infraction: The call was not clear or conclusive. Two sub-categories, “Leaning Infraction” and “Leaning No Infraction,” are included in these “judgment calls” to make eventual datasets more robust.
- Enhanced Review: A conclusive decision on a call could have been reached only using enhanced video review and could not have been reasonably seen by a referee in real time. For instance, the league won’t punish a referee for missing a travel on a play in which slow-motion video revealed that a player lifted his pivot foot milliseconds before the ball left his hand for a dribble.
Reviewers have access to a minimum of nine broadcast angles for every play, plus often several additional views — and a full suite of video enhancement options at their disposal. In addition to entering one of those four tags for each play, reviewers also use video to determine which referee on the court should have been responsible. (Tracking technology also often plays a role in this task.)
A collaborative spirit is encouraged. Reviewers are in the same physical location in Secaucus and often canvass one another or senior staffers on tough plays. (COVID-19 protocols have interrupted parts of this in-person coordination over the past two seasons.)
After six to eight hours, a reviewer will have analyzed a single NBA game and all possible infractions within it. This process will often then be repeated by a senior reviewer on the staff; hundreds of NBA games each season each get 12 to 16 hours of review.
Each call and non-call will be automatically assigned to the referees who worked that game and compared to the reviewers’ tags. (It’s important to note, again, that reviewers are evaluating infractions , not referees themselves. Their job is to focus solely on the players on the court and whether rules were broken during the course of play; to avoid bias as much as possible, resulting grades are assigned to officials later and by other league staff.) This allows for corresponding accuracy to be determined. From here, this data will become part of each official’s existing record. Leaguewide, this dataset is massive: A single season will include around 500,000 refereeing data points, per Evan Wasch, the NBA’s executive vice president of basketball strategy and analytics.
Wasch oversees Angel’s department, which includes a group of data scientists whose role involves combing through this data in excruciating detail. They’re looking for trends across individual refs and and throughout the staff, among players and teams, and even within betting patterns. Wasch’s team will then work with other key NBA officials — including Monty McCutchen, senior vice president for referee development and training, and Mark Wunderlich, vice president of referee operations — on what they find.
This data analysis will often have a direct effect on ongoing referee training. For example, as the game has undergone a spacing revolution in the last decade, officiating analysts began noticing related positioning issues.
“[As] the game became more perimeter-oriented, we found that we were seeing errors in different places on the floor,” Wasch tells FiveThirtyEight. “Which in turn led us to work with Monty and Mark Wunderlich and his staff to rethink referee mechanics to make sure referees were in the right position to pick up plays.”
Again, collaboration is key. Wasch and his staff are regularly embedded in meetings and training sessions with Wunderlich’s group. If data can identify or strengthen an important training area for a single ref, a group of refs or even every ref in the league, all the better.
And they even review their own reviewers! Data is kept on how often senior review staff is forced to overrule an improper tag from an initial review upon their second pass; Angel and his staff address any error trends that show up here. If the issues persist, a reviewer might have to find a new job.
Coming Wednesday: How the ref-grading data is used by the league and its teams.
CORRECTION (Feb. 22, 2022, 3:27 p.m.): An earlier version of this article incorrectly characterized the department within the NBA that handles game analytics. It includes a group of data scientists who sift through the ref data looking for trends.
Ben Dowsett is a writer and videographer based in Salt Lake City. His past NBA work can be found at ESPN, GQ, The Athletic and elsewhere. @Ben_Dowsett
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The refs that botched the knicks-rockets game should be punished by the nba, share this article.
This is For The Win’s daily newsletter, The Morning Win. Did a friend recommend or forward this to you? If so, subscribe here . Have feedback? Leave your questions, comments and concerns through this brief reader survey ! Now, here’s Mike Sykes.
Good Morning, Winners! Thanks so much for rocking with TMW today. We appreciate you. I hope you’re having a fantastic week so far.
You’re having a much better week than Ed Malloy’s officiating crew last night.
I’m sure you’ve seen it by now, but the officials in the Knicks-Rockets game essentially handed Houston a win. Aaron Holiday was rewarded with a phantom foul call on a late 3-point shot after Jalen Brunson gave a good closeout. He hits the free throws and the Knicks lose, to make a long story short.
In the official pool report after the game, Malloy — who was the crew chief for the night — admitted that the call was erroneous after looking at a video review .
“The contact which occurred after the release of the ball therefore is incidental and marginal to the shot attempt and should not have been called,” Malloy told reporter Fred Katz, who got the pool report. But by then it was too late — the call was made and the game was over.
As our Prince Grimes writes here , it’s possible that the Knicks would’ve lost the game anyway. But that’s not the point here, he explains:
“Of course, it’s possible the Knicks would have still lost in overtime if no foul was called, but I’m sure they would have appreciated the opportunity to find out. Especially considering they came back from an 11-point fourth-quarter deficit to tie the game.”
Making that call completely changed the outcome of the game right then and there. If the Knicks were to protest the loss, there’s likely nothing that would come from it. There’d still be another L on New York’s record and with how tight the standings are in the East, that could come back to haunt the team.
I’m not normally one to advocate for punishment in sports. It’s just sports at the end of the day. And, to be clear, officials are punished for making bad calls in the NBA at times. They get pulled off assignments and shifted around — but we rarely see it happen.
But this can’t just be a “my bad” situation — something should be done. Whether that’s the NBA suspending the crew or simply sitting the official who made the call down, I’m not sure. But something needs to be done.
It’s not going to take away from the Knicks’ loss here. But it’d at least ensure that there’d be some tightening up on the referee’s end from here on out.
So what do we think, folks? Should there be a punishment? Here’s a quick poll for you to let us know your thoughts . Let us know what you think.
I’ll reveal the results in Thursday’s newsletter.
The 49ers just need to lie
(Photo by Ezra Shaw/Getty Images)
I need the 49ers to learn how to lie. Because what’s happening right now is just embarrassing.
The team had no idea what the rules for overtime were in the playoffs . That’s embarrassing enough as is. We should probably just leave it there, right? Right? Wrong, apparently.
But now, Kyle Shanahan is telling people they chose to receive the coin toss because “we wanted the ball third.” THIRD? WHAT? EXCUSE ME? Charles Curtis has more here .
“The San Francisco 49ers head coach has addressed why he wanted his team to start overtime in the Super Bowl with the ball — his idea was, if they scored and the Kansas City Chiefs matched, the Niners would get the football in a sudden-death situation. Now, that’s all fine and good in theory (if your team knows the new-ish playoff overtime rules , and some of his players admitted they didn’t ). But the team that possess the ball second has some advantage — they know if they need a field goal to tie it back up or a touchdown to win. It’s four-down territory all the way, too, which means play calls can be more diverse.”
In theory, as Charles said, that makes sense. In practice? Whew, boy. The 49ers were cooked as soon as the game went into OT. That’s becoming abundantly clear. And that’s why folks are roasting Shanahan today.
It’s Victor Wembanyama’s world
(Photo by Cole Burston/Getty Images)
The rest of us are just living in it. The Raptors found that out the hard way on Monday night.
Triple-doubles with blocks are always impressive. But the way Big Vic did it was so destructively thorough. It’s no wonder Scottie Barnes left the court early . I might never pick up a ball again after seeing that.
Get this. Wemby put up 27 points, 14 rebounds, 10 blocks and five assists. He’s one of eight players in league history to have a 25-10-10-5 stat line but also the only one to do it in less than 30 minutes.
LESS THAN 30 MINUTES, Y’ALL. What’s your favorite show right now? Chances are a full episode probably ended before Wemby was done annihilating the Raptors.
We should’ve known what time it was when he showed up to the game like this.
Wemby's pregame fit 👀🔥 pic.twitter.com/5FGWAjHkVx — Bleacher Report (@BleacherReport) February 13, 2024
Victor Wembanyama. Destroyer of Worlds.
Quick hits: Chris Jones is the hero of the Super Bowl … Who stands in the Chiefs’ way? … and more
— Robert Zeglinski detailed how Chris Jones completely saved the Chiefs in the Super Bowl here . They better pay that dude.
— Cory Woodruff has 10 teams that could stand in the way of a three-peat for the Chiefs … including the Cardinals???
— Kyrie Irving is picking Sabrina Ionescu against Steph Curry . That might be good money, folks. Meg Hall has more.
— Tiger Woods’ new brand looks so cool. Charles Curtis explains it all here.
— Here’s Christian D’Andrea with three things the 49ers need to do to break through and win a Super Bowl.
— SHOHEI OHTANI IS BACK, FOLKS !
That’s all, party people! Until tomorrow. Remember, tap into our poll to let us know what you think about the Knicks’ situation. I’ll bring the results back on Thursday!
Be safe out there, folks. Peace. We out.
What are the highest scoring nba all-star games in league history, mic'd up video shows george kittle missing a super bowl loose ball because he was saying hi to the chiefs' george karlaftis, mac mcclung won the 2024 nba slam dunk contest (again) and these were all the best photos, fans roasted kenny smith after he said sabrina ionescu should have had shorter 3-point line vs. steph curry, 3 absurdly wrong lessons other nfl teams shouldn't take from the chiefs' super bowl win, nascar at daytona: starting lineup for 2024 daytona 500 and paint schemes for all 40 cars, guy fieri, jake from state farm and other celebrities who attended 2024 nba all-star weekend.
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NBA Referees to Begin Wearing Sponsorship Patches at All-Star Game
A new NBA partnership was announced Thursday that will result in NBA officials wearing sponsorship patches for the first time ever.
Emirates and the association announced that the airline is now officially the NBA’s global airline partner. As a result, Emirates is now the title partner of the NBA Cup , previously named the NBA in-season tournament. NBA officials will sport an Emirates patch starting at the 2024 NBA All-Star Game in Indianapolis on Feb. 18.
“Emirates is a world-class airline that shares our commitment to engaging fans around the world in new and creative ways,” NBA deputy commissioner and chief operating officer Mark Tatum said in a press release. “As basketball continues to be recognized as the fastest growing sport globally, this collaboration will showcase the excitement of the NBA to the millions of people who fly Emirates every year.”
WNBA officials will start to wear the patch in the 2025 season, and G League referees will start wearing them in the 2024-25 season.