Automated line calling removed a tolerance nobody wrote down

Human officials applied an unspoken benefit of the doubt, and replacing them with sensors changed the game more than the laws did.

A line judge who was not sure said nothing, and the ball was in. That was not written anywhere. It was a habit produced by the cost of being wrong out loud in front of fifteen thousand people, and it meant the practical boundary of the court was very slightly generous.

Take the human away and the boundary snaps back to the paint.

I am in favour of the technology, so start there. Automated calling removed the ugliest scenes in the sport and it removed the suspicion that the biggest names got the benefit of marginal calls in the fifth set. Those were real problems and they are gone.

But the sport should be honest that it changed the rules while claiming only to enforce them. A serve that clips a millimetre of the line is now an ace where it might once have been called long. A player who used to construct points with a margin from the line because the margin was cheap is now rewarded for hitting closer, because closer is reliably rewarded rather than occasionally punished by a nervous official. Over a season that is a shift in what the game asks of a player, produced by an enforcement change rather than by any decision about how tennis should be played.

There is a second loss that gets dismissed as sentiment. The challenge was a strategic object. A player chose when to spend one, held one back for a moment that mattered, and the crowd watched the replay together. That was a genuinely good piece of sport design, and automated calling deleted it by making it redundant.

The part that deserves more scrutiny is what happens when the system fails. A missed call from a sensor failure is handled by the chair umpire under a protocol most spectators have never read, sometimes with a point replayed, sometimes with a decision made on the umpire's own view of what happened. That is a return to human judgement at exactly the moment everyone has stopped expecting it, and there is no challenge available against it.

So the sport has removed discretion from a thousand routine calls and concentrated it in the rare, high-pressure one.

That is not obviously an improvement in fairness. It is a redistribution of it.