There is no shortage of complaining to the officials in an NBA game.

But this year is the first time coaches can do something about it if they think an official has erred.

The league has been experimenting with a new coach’s challenge in which three types of calls are up for review — fouls, out of bounds and goaltending/basket interference. Like the NFL and its red challenge flag, coaches have to signal when they want a challenge by calling a timeout and then waving their index finger in the air, which then sets off a little green light near the bench indicating a challenge is in progress.

It’s all very formal, but it lacks the dramatic throwing down of the NFL flag that some have taken to doing.

Like the rest of his colleagues, Wolves coach Ryan Saunders has been feeling out how best to use this new weapon.

“Typically you’ll try to save it until late,” Saunders said. “If you can take points off the board, that’s a positive, and we’ve done that before, but we’ve also tried to be strategic with it as well. We’re getting better with it.”

That’s true. Saunders has had seven challenges this season, according to data from the NBA. The results were mixed. His first four were unsuccessful. His past three have worked, but even those that were deemed unsuccessful had aspects of the play overturned in the Wolves favor, and vice versa. Saunders has challenged foul calls six times. The other was a basket interference call on Karl-Anthony Towns that didn’t go his way in a game against Memphis.

Saunders isn’t alone in making the majority of his challenges related to a foul call. Through Dec. 19, the NBA said there had been 253 total challenges. Of those, 213 had to do with a foul. Eighty-seven, or 41%, of those challenges were successful.

Coaches have challenged only 31 out-of-bounds calls, 22 successfully (71%). There have been nine goaltending challenges, five successful.

“I can probably be firm in saying it’s not going to be perfect this year for anybody, but it’s going to be an ongoing process,” Saunders said.

It might come as no surprise that most coaches have opted to use their challenges late in the game, with 51% of all challenges coming in the fourth quarter. Four of Saunders’ challenges have come in overtime or the fourth quarter.

Saunders has to move quickly if he is going to challenge. According to the rules, coaches have to make a decision immediately after the play occurs, or they have 30 seconds if there is an opposing team timeout or a mandatory timeout on the floor. In that time, Saunders is looking for any information he can get. Associate head coach David Vanterpool will compile thoughts from the other coaches, and then Saunders will turn to him for the consensus — challenge or don’t challenge?

“They bring all their suggestions to one guy and he kind of makes the call from where the group just said,” Saunders said. “Then I look back and I make the ultimate call.”

Players on the floor have a voice, too. But if they’re going to advise Saunders to use a challenge, they said they have to be absolutely certain the call was incorrect.

“Some plays we know, but there could be some that kind of go the other way,” forward Robert Covington said. “Some of them I’ll be like, ‘Ryan, nah.’ We just have to bite the bullet in certain situations because it’s too unclear.”

It might not stop anyone from complaining about the call, though.

Correction: Previous versions of this article misstated the proportion of successful coach's challenges in the headline.