Only tennis die-hards pay attention to “Next Gen” tournaments—ATP events specifically for under-21 players—but if you had been at the Next Gen finals in Milan last November, you might have noticed something unusual: There was no one making line calls during points; the only official on court was the umpire sitting on the high chair at midcourt. The computers took over the actual calls for the match.
The experiment used a more advanced version of the instant replay software that fans of Grand Slam tournaments and other big events see when players challenge individual calls.The technology used in Milan, however, was so strong that the system made every call, on its own, in real time. The chair umpire was only really there for window-dressing: As someone to keep track of the score and interact with the players should they need, for instance, an injury timeout. And by all accounts the computers did a good job.
Are computer linesmen the future of tennis? The technology is already very good, and will only get better. Rebel Good, a veteran linesman, predicts in the long run, “Line officials probably have as much future as newspapers.”
Here’s how the computer line judge, called “Hawk-Eye,” works now: Human line judges call each shot of a tennis match and players have a limited number of challenges available to them. If they don’t like a call, play stops and a video-animation hybrid of the shot is displayed on the court’s main screen. These videos are not actual images of the ball in question as it lands on the court: They’re a representation drawn from the algorithm the technology uses to analyze every shot, based on information gathered by cameras placed around the court which track how fast the ball is moving at what trajectory. If this sounds like it could go wrong, well, yes. Hawk-Eye doesn’t tell you where the ball landed—it just tells you where it guesses the ball should have landed. There are technical limitations to this estimation, primarily tied to camera frame-rates. Because of that, Hawk-Eye has had a few high-profile mishaps, but the larger question about it, as far as accuracy goes, is why Hawk-Eye isn’t transparent about the fact that it has a margin of error.
But even if you’re willing to stipulate that Hawk-Eye is just as accurate—or even more accurate, on average—than carbon-based line judges, is it really better?
Imagine simply hearing a recorded voice announcing every miss, including service faults, for an entire match. An electronic voice could be developed to announce calls, but it wouldn’t be like the sounds and variances you get from having a crew of judges working a match. And gone would be the occasional dramas of the replay challenge: With Hawk-Eye as the sole arbiter, there would be no way for players to protest a call. Hawk-Eye would be the voice of God.
Never lose sight of the fact that the point of tennis—of all sports, really—is entertainment, not the achievement of absolute precision at all costs.
When it comes to officiating in sports, we’re constantly trying to hit a Pareto optimum where the accuracy achieved is sufficient to prevent bad calls from impacting the outcome, but the process of achieving this accuracy does not encumber the game.
If the ATP decides to replace line judges with Hawk-Eye, they’ll be making the sport less interesting and enjoyable for—at best—a trivial gain.
“Hawk-Eye is a great invention, and it will only get better,” Rebel Good says. “But if you use it all the time it would be sterilizing. I think people are missing the point.”
