Making sense of the NBA’s challenge system

Brook Lopez said exactly what was on his mind.

“It’s whatever, man. I’m not surprised that they can’t get it right the first time.”

During the Milwaukee Bucks win over the Minnesota Timberwolves on New Year’s Day, Lopez was whistled for a foul on what appeared to be a cleanly blocked shot.

Lopez’s reaction earned him a technical foul, but head coach Mike Budenholzer did throw the imaginary red challenge flag for the referees to review.

After examining the footage, the call was confirmed.

The crowd at Fiserv Forum booed, loudly. Lopez put his hands on his hips and paced with frustration from the bench to the court to line up for Minnesota’s ensuing free throws.

Initially, the question directed to Lopez wasn’t about his anger regarding the call, but whether or not he ever lobbies Budenholzer to use his sole challenge of the game on similar plays.

Coach’s challenges in the NBA are new for the 2019-20 season. They get one per game, no matter the result. Budenholzer has mentioned on numerous occasions that he and the Bucks’ coaching staff is still adjusting to the addition, and there are many factors that go into deciding whether or not to make the call.

Time left in the game, number of fouls on the accused player and likelihood of a successful challenge are all calculated in the 60 seconds or less that a team has to make that call.

The only video they can access is on the scoreboard at the arena, and that video isn’t controlled by NBA coaches. It’s an imperfect science to say the least.

However, as of Jan. 2. 2020, NBA coaches have been successful on 47 percent of challenges.

“In general, the challenge has been, probably, learning when, where and how to use it,” Budenholzer said post-game. “Why they overturn things and they don’t. It doesn’t feel great for anybody so far, but there’s still a lot of the season left.”

The 47 percent over-turn rate is a bit inflated. On fouls called, coaches have won just 42 percent of their rebuttals. The averages increase because ‘out of bounds’ calls are adjusted 78 percent of the time, and ‘goaltending’ is reversed at a 58 percent rate.

As for when challenges are used, league wide there have been a total of 20 used in the first quarter this season. Compare that to the final period of the game where monitors have been called upon 155 times.

Expect Lopez to be in similar situations throughout the season, he’s currently averaging a career best 2.5 blocks per game (85 total) and Milwaukee’s perimeter players have said how they have confidence to funnel opposing offensive players in Lopez’s direction.