The offside trap now belongs to the goalkeeper

A high defensive line is only as brave as the man behind it, and that has quietly changed what clubs need from a keeper.

Watch a side defending forty yards from its own goal and count where the goalkeeper is standing. Frequently on the edge of his own penalty area, sometimes beyond it, walking around like a spare centre back. That position is the whole reason the line in front of him can hold where it does.

The old trap was a defensive negotiation. Four defenders stepped together, timed against the moment the pass was struck, and hoped an official saw it their way. It was a gamble that produced spectacular successes and catastrophic failures, and its failure mode was a striker running clear from the halfway line with nobody within twenty yards.

The modern version is different in kind. The line steps up not to catch anybody offside but to compress the space the opponent can play in, and the ball played over the top is not a disaster because there is a goalkeeper standing thirty yards from his line who will get there first. The offside decision has become a by-product. The keeper is the actual insurance policy.

Which means the position is now selected on a skill that had almost no weight twenty years ago. Reading the flight of a long ball while running backwards, deciding in half a second whether to come or to retreat, and being right nearly every time. That is a different aptitude from shot stopping, and the two do not correlate especially well. Clubs have started paying for it. Some are still buying the best shot stopper available and then asking him to play a system his instincts fight.

There is a cost worth being honest about. The keeper who sweeps aggressively will occasionally be caught out, and when he is, the goal is humiliating and gets replayed for a week. A manager who has committed to a high line has to absorb three or four of those a season and keep his nerve, and most of the criticism will land on the defenders rather than on the design.

Crowds make it worse. The noise that rises the moment a ball is knocked over the top is exactly the environment in which a keeper hesitates, and hesitation is the one response that guarantees the worst outcome.

Pick the line, then pick the man behind it. Doing it in the other order is how good defences end up looking naive.