The offside trap is now a bet on the technology, not on the defender

Automated calls removed the human margin that once made stepping up either a masterstroke or an outrage.

Step up and the whole thing hinges on a measurement taken by a system in another room. That is a different job from the one defenders were doing ten years ago, and I am not sure the coaching has caught up with it.

The old trap ran on human error, in both directions. An assistant referee tracking a fast line from side on had a genuine margin of uncertainty, and defenders played into it. Step early and the doubt was yours, because a flag that goes up cannot be un-waved. The trap was partly a defensive action and partly a psychological one, an attempt to make a human being make a decision quickly.

Automated systems remove the doubt and remove the benefit of it. A limb is where it is. A pass leaves a foot at a defined instant. The margin that a defender was farming has gone, replaced by a binary answer to the nearest few centimetres. That should make the trap more attractive, because it is now a pure geometry problem, and it has instead made defenders more cautious, which I think is a mistake driven by memory rather than analysis.

The reason for the caution is the delay. Under an automated system the flag comes late by design, so a defence that steps up and gets it wrong concedes a goal first and finds out afterwards. Under the old rules the whistle stopped the move immediately. The consequence of a failed trap has grown enormously even though the frequency of failure has fallen, and human beings weight consequence far more heavily than probability. That is the whole psychology of it.

So defences hold a deeper line, which hands attacking sides the space between the lines that everybody spent the last decade learning to attack. I would argue the opposite is correct. If the measurement is reliable, the trap is now a repeatable mechanism rather than a gamble, and the side willing to trust it gets fifteen metres of pitch back.

Somebody will do this properly and be praised for bravery. It will not be bravery. It will be arithmetic that everyone else declined to do.