Evolution of the Coach's Challenge in the NBA: A Comparison Between the 2019-20 Season and the 2023-24 Season

Evolution of the Coach's Challenge image

📖 Published on: May 20th, 2024

✍️ Updated: June 17th, 2024

⏳ 31 mins read


Gone are the days when coaches only had postgame interviews as a platform to vent out their disappointment with the officiating in the game. Most of the time, these stem from controversial calls in a given game, which didn’t go in their favor and sometimes even led to some key losses in their games. But with the Coach's Challenge, basketball tacticians now have a way to plead their case against some calls that they think can be argued about, making it one of the best innovations that the NBA has ever come up with over the years.

Evolution of the Coach's Challenge in the NBA image

What is the Coach's Challenge?

The Coach's Challenge was introduced in the 2019-20 season as an experimental feature in basketball games. It was a one-year trial in the first year, before becoming an official rule in the 2020-21 season. The challenge was implemented to give coaches a way to initiate a contest of a certain play call by the officials in a given game. According to the NBA Official website, a head coach may trigger an instant replay review of a certain play under the Coach's Challenge right. The only plays that can be reviewed are either (1) a personal foul charged to their player, (2) an out-of-bounds violation and a subsequent jump ball, or (3) a goaltending or basket interference play called.

Erik Spoelstra complaining a call to the referee image

Initially, the Coach's Challenge will need the coach to call a timeout in exchange for the right to challenge the call and initiate a play review. Each coach has a right to challenge at least once in a single game, and it has been amended to give coaches an additional challenge should they be successful in their first attempt. However, the timeout used to initiate the second challenge will be lost regardless of the result, meaning that coaches will only have a maximum of two challenges in a given game.

Once initiated, the officials will now signal the green light on the sideline to denote that a Coach's Challenge is active. The three officials will discuss the play in contention together with the help of the NBA Replay Center in Secaucus, checking all of the best angles possible to come up with an informed decision regarding the challenge.

Doc Rivers arguing a crucial call from the referee image

It will either result in a successful challenge for the team, with the call being overturned and now in favor of the challenging coach’s team – or the call stands and the coach loses his timeout and the right to challenge another call for the remainder of the game. In either result, the officials will deliberately explain how the call either stays the same way or what was considered for the call to be overturned.

Why Add the Coach’s Challenge?

The Coach’s Challenge was not added until the 2019-20 season, which just means that there were a lot of steps that took place before it was certainly added to the NBA’s mix of new features over the years. Of course, one of the biggest factors that forced the NBA’s hand to come up with this feature is the number of issues, criticisms, and coaches coming up with comments against the officiating of NBA officials.

So what are the biggest instances that paved the way for the Coach’s Challenge to be introduced in the NBA?

Take That For Data

One instance was in April 2017, where the Memphis Grizzlies were defeated by the San Antonio Spurs in a 96-82 win in Game 2 of their first-round Playoff series. Grizzlies coach David Fizdale went irate in the postgame interview as he ranted to the press with numbers that didn’t make sense.

Take that for data image

The Grizzlies shot the ball 35 times in the paint, which is an area where most fouls are called, only to come up with 15 free throws for the whole game. On the other hand, the Spurs, who were a promising shooting team at the time, only attempted 18 shots in the paint while having 32 free throws. On top of that, Kawhi Leonard had 19 of those 32 foul shots, which definitely fueled Fizdale’s iconic “Take that for Data” line in criticism of the officiating calls in that game.

2007 NBA Betting Scandal

In 2007, there was also a known NBA betting scandal with accusations on referees, coaches, players, and even owners betting on professional basketball games. It would later turn out in July 2007, based in an report of the Federal Bureau of Investigation what went public, that referee Tom Donaghy wagered on games in which he officiated from the 2005-06 and 2006-07 seasons.

Tim Donaghy was at the forefront of the 2007 NBA Scandal image

This meant that he was altering game outcomes, coming up with blatant calls that were affecting the results of the game. Former NBA commissioner David Stern said at the time that "no amount of effort, time or personnel is being spared to assist in this investigation, to bring to justice an individual who has betrayed the most sacred trust in professional sports, and to take the necessary steps to protect against this ever happening again." Donaghy was sentenced to 15 months in prison with three years of supervised release, and was also banned from being involved with the NBA again.

Reputation of Known Referees

On top of that, a lot of known NBA officials were often associated with coming up with phantom calls in a given game. We have seen the likes of Joey Crawford, who is notorious for ejecting Spurs big man Tim Duncan just for laughing on the bench. There’s also Scott Foster, nicknamed “The Extender” as most of the trailing teams in any playoff series have won the games where he was officiating. An anonymous survey among 108 NBA Players by the Athletic in 2023 voted him as the worst referee in the NBA, on top of having a close relationship with former NBA referee Tim Donaghy.

Joey Crawford is known well for ejecting Tim Duncan for laughing from the bench image

Scott Foster was infamously known as "The Extender" with his blatant calls image

As a result, the Coach’s Challenge was later formulated to address the needs of coaches in terms of contesting questionable calls. It also served as a way to safeguard the integrity of the game in ensuring that game-fixing and other possible nuisances will be averted, bringing the NBA to bigger heights of engaging basketball.

Inconsistencies and Updates

Of course, not all coaches have seen great success with the Coach's Challenge over the years. There are also times when the Coach's Challenge proves to be tricky with multiple changes in the rule from time to time, and sometimes the NBA doesn’t announce it right away via the NBA Communications – making changes in the middle of the season or even in the Playoffs.

One instance was with Oklahoma City Thunder head coach Mark Daigneault – who is one of the successful coaches when it comes to the Coach's Challenge. In OKC’s Game 1 win over the New Orleans Pelicans, a pass by OKC center Chet Holmgren got deflected, with players from both teams fighting for the loose ball before it went out of bounds. With the game officials not knowing who touched the ball last, they elected to call a jump ball instead.

Mark Daigneault, the 2024 COTY, argued inconsistency in the Coach's Challenge image

Daigneault challenged the call, with the hopes of getting the best possession. The review showed that the Thunder touched the ball last, which meant that New Orleans got the possession. While they didn’t get a favorable call, OKC retained its challenge and timeout since it was considered successful. However, the officials would later change the ruling with 2:40 left in the game, deeming OKC’s challenge unsuccessful. OKC went on to win the game at 94-92, but Daigneault was not pleased with the actual result of the challenge.

"I just looked it up because I wanted to make sure I wasn't crazy," Daigneault said. "I don't think I'm wrong because it happened during the year. But if it was wrong in Utah, I didn't get a phone call. I've gone the whole season understanding the rule like that. I was very confused just because it's a huge inconsistency. If it was wrong in Utah, I wish they would've called me. If it was wrong tonight, it's a playoff game. I was a little disappointed in that one."

In a January 18 regular-season road win over the Utah Jazz at 134-129, a similar situation was encountered by Daigneault and the Thunder. However, the jump ball call was overturned, and the challenge was deemed successful with the Jazz earning possession of the ball.

Another instance was Boston Celtics head coach Joe Mazzulla’s decision to challenge a call that was against them – while the team is up by 27 in their game against the Toronto Raptors with just 3:39 left in the game. The NBA has maintained promising focus in the game, having a short delay in their game before finally coming up with a decision to overturn the out-of-bounds call, showing how each of these challenges are handled with extreme sensitivity at all times.

Joe Mazzilla argued a call in the out of bounds image

Coach's Challenge: Calls that Can Be Challenged

Not all calls can be challenged by the team in every single game. As said above, the challenges are limited to personal fouls, out-of-bounds plays, and goaltending or basket interference calls. Learn more about these respective calls below:

Personal Fouls

A personal foul can be challenged image

Personal fouls are the most common offense that a player can commit in the NBA. These are called when a player is deemed to make illegal contact with an opponent, which disrupts the game. These can be in the act of shooting, in which a player contests a shot attempt from an opposing player. A defensive foul is a rough defense on a player-initiated by consistent shoving, blocking a player’s path to the basket, and so on. An offensive foul, on the other hand, is committed with excessive contact, such as using an elbow, charging through a defending player in a restricted area, and so on.

Out of Bounds

Out of bounds calls are challengeable image

An out-of-bounds call is made when the player is sent out of the playing area, or the player holding the ball steps on the sideline. A ball that is shot and goes up behind the backboard or enters the cylinder from below is considered a ball out-of-bounds. If both players had touched the ball before it went out of bounds, the officials will have to determine who touched the ball last via replay or review, or if all officials are in doubt, a jump ball will have to be done between the two involved players in the nearest circle.

Goaltending/Basket Interference

Goaltending and basket interference image

A goaltending or basket interference is an act in which a player tries to block a shot that has already touched the backboard, or a player trying to put back a shot into the basket after a prior attempt while the basket is still in the cylinder. For goaltending, defending players must not touch the ball after it already made contact with the board. On the other hand, a basket interference is called when an offensive player touches the ball while it is in the cylinder after an attempt from him or his teammate that already has a tendency to go down.

Comparing the Coach’s Challenge Across Different Sports

The Coach’s Challenge isn’t unique to the NBA. We have seen different iterations of the same feature across various sports leagues. Over the years, these has helped refine the Coach’s Challenge in the NBA, helping make adjustments to the rule and devising new advancements to the feature.

Here are the different iterations of the Coach’s Challenge in other sports leagues:

VAR in the EPL

VAR in the EPL served as a re-review of crucial calls image

At first, it did seem that many managers seem to question the point of VAR, the Video Assistant Referee. However, as time went by, VAR became a reliable addition to soccer with the help of AI, which helps review a certain play in a given game. This concerns offsides, blocked goals, illegal tackles, and many other concerns. It was originally designated to review a goal or no goal situation, but was later expanded to player offenses, handballs, and even excessive foul contacts between players.

Manager’s Challenge in the MLB

Replay review was initiated in the MLB back in 2008, before being expanded in 2014 by giving managers at least one challenge to start the game and another challenge should the first one be a successful challenge. It was later amended with managers now allowed to challenge during an inning without the need to approach the umpire on the field. In the 2017 season, the challenge was given a 30-second limit, with managers allowed to initiate a contest during that timeframe. The most recent amendment in the MLB’s Manager’s Challenge was to shorten the timeframe to 20 seconds for managers to invoke the challenge.

Managers can initiate their own challenge in the MLB with a monitor image

Red Flag Challenge in the NFL

Coaches can challenge play calls in the NFL with a red flag image

The NFL initially had an Instant Replay feature way back in 1986. The league was the proponent of the concept of challenging play calls in sports as they introduced the so-called “Red Flag Challenge” in 1999. Each coach was given two changes in a game to initiate and contest a call by umpires. In 2004, this was amended to award a third challenge if at least one of the two original challenges were deemed successful. An instant replay booth is placed in the stadium for reviewing scoring plays, out of bounds, ejections, passes and fumbles, recovery of looseballs, and many other calls.

How the Coach's Challenge Has Evolved Over the Years

Since its inception, the Coach's Challenge has been one of the biggest features added to the NBA, and it cannot be denied that teams and coaches have struggled to adapt to the new rule at first before finally finding a full understanding of the rule. To dive deeper into the changes in the Coach’s Challenge and its use over the years, we have tallied the data between its inaugural season in the 2019-20 season, and the current campaign, the 2023-24 season.

Coach's Challenge Analysis: 2019-20 Season

In the 2019-20 season, there were a total of 633 challenges initiated by coaches, with 281 of those deemed as successful challenges for a 44.4% overturn rate. This only takes into account the challenges that were initiated only in the regular season, excluding all games in the subsequent playoffs. It is also worth noting that there are only a total of 63 to 67 games played between the teams as the season was suspended on March 11 due to the COVID-19 pandemic.

CALLED FOUL 542 214 328 40%
OUT OF BOUNDS 69 52 17 75.4%
TOTAL 633 281 352 44.4%

Most of the time, foul calls are challenged throughout the season, with the overturn rate being set at 39.5% of the time, meaning that NBA officials are mostly correct in their foul calls in almost every single game. However, the out-of-bounds challenges finished with a staggering 75.4% overturn rate, meaning that the coaches made the right decision to challenge the referees’ calls when it comes to possession for balls coming out of bounds. A total of 52 challenges were successful over 69 challenge attempts in all out-of-bounds calls. For goaltending and basket interference calls, 22 challenges were attempted, with 15 of those being successful for a 68.1% overturn rate for the whole season.

Quarter by Quarter Analysis: 2019-20 Season

For the 2019-20 season, there has been a noticeable trend in the volume of challenges made in each quarter. For instance, the first quarter has a total of 43 challenges (35 foul challenges, 7 out-of-bounds challenges, and one goaltending/basket interference challenge). This significantly increases in the succeeding quarters, with 99 challenges in Q2, 163 challenges in Q3, and a whopping 315 challenges in the fourth quarter and overtime combined. It does seem that most coaches were electing to save up their challenges until the final moments of the game.

CALLED FOUL 35 88 134 284 N/A 542
OUT OF BOUNDS 7 8 21 33 N/A


TOTAL 43 99 163 327 N/A 633
OVERTURN RATE 63% 54% 44% 39.4% N/A 44.4%

Based on the data for the Coach’s Challenge in the 2019-20 season per quarter, coaches have forced the best overturn results in the first quarter, with a success rate of 62.8%. This is followed by the second quarter, which has an overturn rate of 53.5%. However, the third quarter and fourth quarter/OT overturn rates are significantly lower than the first two, with Q3 overturn rates at a 44% overturn rate, followed by the Q4/OT overturn rate of 39.4%.

Coach's Challenge Analysis: 2023-24 Season

In comparison to the 2023-24 season, it seems that there is a spike of challenges attempted by coaches, showing how they have acclimated to the new feature in the span of four years. There are also significant increases in the overall challenge issued in each reviewable call from the referees. For instance, from a total of 542 challenges, foul calls were contested 955 times, with the overturn rate up from 39.5% to 52.3%, which meant that coaches were also knowing which foul call to challenge.

The same can be said for out-of-bounds plays, which drastically increased from 39 total challenges in the 2019-20 season to a massive 348 challenges this season. On top of that, coaches still have found accurate contentions on that end, with a 75.4% overturn rate to a 78.5% mark this season. However, while the goaltending/basket interference challenges were a +15 with a total of 37 contentions, the overturn rate went down to 65%.

CALLED FOUL 955 499 456 52.3%
OUT OF BOUNDS 348 273 75 78.4%
TOTAL 1340 796 544 59.4%

Still, there has been a significant jump in the number of challenges attempted by coaches in the season. The 2019-20 campaign saw 633 challenges with a 44.4% overturn rate, and this season went up with a total of 1,340 challenges for the whole season. On top of that, the overturn rate skyrocketed to an all-time high of 59.4% overturn rate. It should also be noted that the 2023-24 season completed a total of 82 games, as opposed to the 2019-20 season, with teams finishing from a range of 63 to 67 games due to the COVID-19 pandemic.

Quarter by Quarter Analysis: 2023-24 Season

There is a huge difference in the number of challenges attempted per quarter from the inaugural 2019-20 season and the 2023-24 campaign. The first quarter totals were up to 134 compared to 43 in 2019-20. The same can be said for the rest of the quarters, with Q2 totaling 268 challenges (99 in 2019-20), Q3 amounting to 349 challenges (163 in 2019-20), and Q4 (excluding overtime) totaled a whopping 576 challenges (327 in 2019-20). This just goes to show that the strategy of keeping a challenge all the way to the fourth quarter has become mainstream, with coaches also having an additional challenge at their disposal should they have come up with a successful challenge in their first attempt.

CALLED FOUL 94 195 250 406 10 955
OUT OF BOUNDS 37 65 85 160 1


TOTAL 134 268 349 576 13 1340
OVERTURN RATE 69% 66% 65.4% 51.1% 46.2% 59.4%

For instance, the first quarter totals were up to 134 in 2023-24, compared to the total of 43 challenges in 2019-20. The overturn rate has also made a small jump from 63% to 69% in the current season, showing how consistent it is compared to the past few seasons. All individual challenges also saw an increase in the overturn rate compared to the 2019-20 season. In the second quarter, it is notable that there has been a jump in the overturn rate from 54% to 66%. Overturn rate in all challenge types have been remarkable as well, with called fouls overturned 56.4% of the time, out-of-bounds calls overturned 91% of the time, and goaltending/basket interference calls corrected 88% of the time.

Third-quarter totals made a significant leap in the overturn rate as well. There’s no denying that this is considered one of the most important quarters in the game as it is the chance for teams to set the tone for their respective games, come up with a promising lead, or put the game away for good. The success rate saw a 20% jump with 349 challenges amounting to a 65% overturn rate from a 44%% mark in the 2019-20 season. The fourth quarter is the most important part of the game, without a doubt, and we have seen a massive spike in the volume of challenges at this point in the game. It is also worth noting that teams will have only two timeouts in the final two minutes of the game – making the challenge a “use-it-or-lose-it” scenario. With that being said, the coach’s challenge in the fourth quarters of the 2023-24 season has seen a promising leap. There were a total of 327 attempts in the 2019-20 season, and the 2023-24 season doubled that amount with 576 challenges attempted in the fourth. The success rate has also been promising with a jump from 39.44% to a whopping 51.2%.

Importance of the Coach's Challenge

The Coach's Challenge has been considered one of the best innovations in the NBA over the years. Just like in the MLB and the NFL, coaches in the league now have the chance to appeal certain decisions from the officials in real-time. Of course, the rules for officials to trigger a replay remain the same, but the coaches are now armed with a sense of control, at least once or twice in a single game. This can be considered a promising tool for coaches to hold on to, especially in the biggest games.

The Coach's Challenge continues to be developed and refined in the past few years image

According to Indiana Pacers head coach Rick Carlisle, the Coach's Challenge gives them a tool to use in the big moments of the game, forcing a review and getting a chance to draw up a play while hoping that the call will be overturned in their favor.

“I’ve been a proponent of it for many years, just as an additional layer of security,” said Carlisle. “If a call’s inaccurate for any reason, it’s just an extra chance — particularly if the game’s on the line — to get it right. The question has always been, how to execute it. Where to start. Sounds like this is going to start with a high level of simplicity. Then we’ll see where it goes.”

Back in the 2017-18 season, the Denver Nuggets missed the postseason thanks to a loss to the Minnesota Timberwolves in their final game of the season, which was a 112-106 loss in overtime. There were multiple calls that didn’t go their way, which later on was reviewed to be incorrect according to the NBA’s Last 2 Minutes Report. Coach Michael Malone expressed his regret in the what-if moments in the game.

“Think about it,” Malone said at the time. “One play could have been the difference for us between the lottery and playoffs. That saves jobs, that gets home/road seeding, there are a lot of things that it can affect.”

2023-24 Coach of the Year winner Mark Daigneault also claimed that the Coach’s Challenge prove to be a great innovation in the game, but also says that it eats up some time in the game, which is why the NBA has to somehow expand and come up with more challenges for them to operate with while not hampering too much of the game’s time.

“But in reality a lot of those challenges would happen during mandatories (timeouts) if they happened earlier in the game, so it wouldn’t change the overall duration of the game,” Daigneault said. “They don’t want to add a bunch of time to the game because of the fan experience, and that’s understandable. But I think that would be a low-cost proposition, and I think the goal would be to operate within that constraint, you know?”

The Coach's Challenge can be refined even more with new features image

It cannot be stressed enough that the Coach’s Challenge has given the NBA a significant value for fans to watch, and a promising tool for coaches to make use of when it comes to giving their respective teams an edge. This is why the evolution of the Coach’s Challenge in the NBA is a testament to how effective it has been in enhancing the game for a much more promising and more balanced competition between the best teams in the league.

The Future of Coach’s Challenge in the NBA

With all the data analyzed along with testimonials from coaches, players, and officials put into consideration, there’s no doubt that the Coach’s Challenge in the NBA has a long way to go in refining the Coach’s Challenge to make it the best version of it as possible. With the help of comparative data in the league and varying concepts from other sports leagues, this would be a promising chance to create alternatives and tweaks to make the Coach’s Challenge a better feature in the game.

Here are some key suggestions that should be taken into consideration for further improvement of the Coach’s Challenge:

Additional Challenge

Like in the NFL, a third challenge should be added to the NBA’s own version. A successful challenge for the first two tries should reward coaches an additional challenge that can help them well in the game. This can be a crucial shift since challenges, especially in the fourth quarter, are mostly used to contest crucial play calls, which should definitely impact game endings as a whole.

An additional challenge will be beneficial to coaches image

An additional challenge would also give coaches a chance to make the best out of their final timeouts, especially with two timeouts left in the game when it approaches the final two minutes. Imagine being successful with the first two challenges and having an additional challenge in the dying moments of the game.

Removing the Use of a Timeout

Timeouts serve as a trading piece for coaches to initiate a challenge in a single game. In each game, coaches have a total of seven timeouts, with any other timeout automatically removed as teams are only allowed to have two timeouts within the final two minutes of the fourth quarter. A successful challenge means that a timeout used will be returned, but the timeout will be gone if it is unsuccessful. This is why the NBA should consider a challenge as a free right for coaches to contest controversial calls – at a limited number at that.

Timeouts are crucial in the game and should not be charged for a challenge image

Removing the need for a timeout to initiate a coach’s challenge will give coaches a bigger freedom to use their timeouts and challenges without the constrictions of losing a timeout. The NBA has its fair share of controversial calls over the years, and it goes without saying that the Coach’s Challenge should be instead considered a constant right for coaches to contest unsure calls in the game.

The Coach’s Challenge: A Promising Feature in the League

There’s no denying that the Coach’s Challenge has become one of the staple and successful features that have been added in the NBA. The innovations and adjustments made to it over the years have helped it become a stabilizing bridge between coaches and the officials, making it a truly fair game for everyone to enjoy. This would also help remove the doubts and criticisms about the officiating in the game over the years.

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