When the green challenge light starts blinking, it usually means the Warriors are about to lose a timeout

Steve Kerr, pleading the referees to let him win a single challenge Photo by Mike Ehrmann/Getty Images

With 8:15 remaining in the first quarter of Tuesday’s win over the Dallas Mavericks, the referees whistled Steph Curry for a blocking foul on P.J. Washington, who also made his shot. But before Washington could step to the line to complete the and-one, the green light on the scorer’s table started flashing, and Golden State Warriors fans familiar with Steve Kerr’s challenge record cringed.

Through the games of March 2024, NBA replay challenges were more successful than not. Out of 1,214 challenges, 714 led to officials’ calls being overturned, a 59.5% success rate. Coaches disputing out of bounds calls was most successful, working 77.7% of the time, while foul calls were overturned 53% of the time. Goaltending and basket interference challenges are rarest, with only 34 all season, of which 21 were successful.

Calls are most likely to be overturned in the first quarter and least likely in the fourth, which reflects the risk/reward calculus for coaches more than the quality of calls. Coaches want to be fairly sure when using a challenge early, and those work almost 70% of the time. Fourth quarter challenges are often made out of desperation, or when coaches would be calling a late timeout already. and only 51.4% of them are overturned. In OT? Only 36.4 % of challenges pay off.

According to X user @DesertSquirrel2 (only the finest sources here at GSOM!), Kerr is now 15-29 in replay challenges after his unsuccessful effort Tuesday, a success rate of 34.1%.

To put this in the context of NBA lottery teams, Kerr wins challenges at a slightly lower rate than the Memphis Grizzlies win basketball games, the 7th-worst rate in the league.

Kerr has by far the worst challenge percentage this season, but the rest of the bottom ten is fascinating. The Toronto Raptors’ rookie coach Darko Rajaković is second-worst at 45%, then Monty Williams of the Detroit Pistons at 48%, because Detroit simply can’t win. But jut below Williams and also at 48% are Mike Brown of the Sacramento Kings and New Orleans Pelicans coach Willie Green — both former Steve Kerr assistants.

There are reasons why Kerr’s numbers aren’t that high. He will often use a challenge when he would have called a timeout anyway late in games, figuring that a successful challenge is just a bonus. Kerr also listens to his veterans, who are often not good at judging whether or not they committed a foul. Perhaps losing a timeout is preferable than listening to a player complain — we’re not naming any names — on the bench, or on his podcast, “The Draymond Green Show.”

But it also seems like Kerr and his staff just aren’t very good at judging these calls themselves. Does the Chase Center need to improve the speed and quality of its Jumbotron replays? Can Joe Lacob hire Steve Javie to analyze calls from a wine cellar below the court? Would the replay center in Secaucus appreciate a shipment of unclaimed Andris Biedrins bobbleheads for some extra consideration?

It’s best to interpret most of Kerr’s challenges as being in the service of his players, like when a baseball manager gets himself ejected to keep his slugger in the game after a ball-strike call. It’s also best to never get your hopes up about a Warriors challenge, because roughly 66% of the time, you’re going to be disappointed, no matter how strongly Bob Fitzgerald feels about the incorrectness of the original call.

In the rest of the world, a green light means “Go.” At a Warriors game, it means “Go figure out how we can deal with the timeout we’re about to forfeit.”