Video review quietly retired the offside trap

When flags are held and margins are measured in centimetres, stepping up as a gamble stops paying and starts costing goals.

The trap was always a bet. Step the line forward at the right instant, the striker is caught, the flag goes up and the danger ends immediately. What made it worth playing was the immediacy. Even when the officials got it wrong in your favour, the whistle stopped everything, and even when they got it wrong against you, the mistake was over in a second.

Two changes killed that. First, assistants are now instructed to keep the flag down on tight calls and let the phase finish. Second, the review measures to a body part. Put those together and the arithmetic of the trap inverts. You step, you win the offside by two centimetres, and the attacker still runs through, still shoots, and if the frame chosen for the kick is a fraction late, or if a knee is judged to be ahead, the goal stands. Meanwhile every defender behind the ball has stopped and raised an arm.

So the downside is now unbounded and the upside is a delayed decision you cannot see. No sensible defensive coach takes that bet often.

Watch what teams do instead. They defend the depth. The line sits five to eight yards deeper than it would have fifteen years ago, the last defender turns and runs rather than stepping, and the space in front of the back four gets handed to the opposition midfield on the assumption that a shot from twenty five yards is a cheaper concession than a run through on goal. I think that is the correct read, and I also think it has made a certain kind of game duller.

There is a physical consequence nobody talks about. A trap is a step forward, which is a cheap action. Defending depth means turning and sprinting backwards at speed, repeatedly, often with a striker in contact. That is one of the highest strain actions in the sport, and asking a thirty three year old centre back to do it fifteen times a match is a different job description than the one he learned.

Semi-automated systems have made the calls faster and more consistent, which is good. They have not restored the trap, because the problem was never accuracy. It was that the flag stopped going up early, and no technology is going to put that back.