Half the teams copying the inverted full-back cannot afford it

The move only works if three other things are true, and most sides borrowing it have exactly none of them.

A full-back stepping into central midfield when his team has the ball is a genuinely clever idea. It gives you a four-man diamond in the middle, it means the ball can be circulated centrally instead of going round the outside, and it puts an extra body in the exact area you want to win the ball back if you lose it.

It also removes your width, exposes the channel he vacated, and asks a defender to make midfield decisions in a crowd.

The first condition is a winger who can genuinely hold the touchline one against one. Not a winger who drifts inside looking for the ball, an actual chalk-hugger who will stay out there for eighty minutes waiting for a switch and beat his man when it comes. If your wide player also wants to come inside, you now have two players occupying one zone and nobody stretching the pitch, and the opposition defensive block just narrows and swallows the lot.

The second is a centre-back who can defend a lot of ground on his own, because when possession is lost the back line is temporarily a two, sometimes a two and a half, and there is grass out wide where the full-back used to be. If your centre-half is a good header of the ball and slow across it, the first counter-attack of the game will teach you this.

The third is a goalkeeper comfortable playing thirty yards from goal, because he is now the last cover. That is not a preference. It is a job requirement, and plenty of very good shot-stoppers simply do not have it.

What you get instead, in a lot of sides, is a manager who liked the shape on television. The full-back steps in. He is a decent defender and a mediocre passer, so he receives the ball facing his own goal, gets pressed, and plays it back to the centre-half. Nothing has been created. Meanwhile the winger in front of him is isolated with no overlap available and the opposite flank is being attacked into a space with nobody in it.

I am not arguing against the idea. I am arguing against the borrowing of it as a badge of sophistication. The old-fashioned overlapping full-back is a perfectly good answer for a squad built that way, and there is no shame in playing a shape that fits the eleven players you actually own rather than the eleven you watched last Tuesday.