Compactness is a vertical problem and teams keep measuring it sideways

Shuffling everyone across to the ball looks organised on television, but the gap that actually kills you runs from front to back.

Ask most people what a compact defensive block looks like and they will describe width. Ten players squeezed into one half of the pitch, all shifted towards the ball, leaving the far touchline empty because the switch takes long enough for you to slide back across. Correct as far as it goes. It is also the easy half.

The hard half is the distance from the highest defensive player to the lowest. Front line to back line. Get that above about thirty metres and it does not matter how tightly you have packed the sides, because there is now a receiving zone in the middle of your own shape that a decent number ten will find blindfolded. Get it under twenty-five and you are a genuine problem to play through, but you have to accept the ball being played over the top and you had better have a keeper who sweeps and centre-backs who can turn.

What goes wrong is almost never the back line. Back fours are drilled to death, they hold a line, they step together. It is the forwards. A striker who presses a centre-back on his own, gets played around, and then stands there watching the ball travel instead of sprinting back has just added eight metres to the block's height, and every one of those metres is space for the opposition pivot.

So the number I would actually want, if I ran an analytics department, is not compactness averaged over ninety minutes. It is compactness in the three seconds after the opposition's centre-back receives with time. That is the moment of truth. Averages hide it completely, because a team spends most of a match in settled phases where everything looks tidy.

There is a fashion argument here as well. The mid block has been unfairly cast as the poor relation of the high press, something you do when you cannot afford players good enough to press properly. That is nonsense. A well-set mid block that stays under twenty-five metres and refuses to be dragged out is one of the hardest structures to break down in the sport, and it costs a fraction of the physical output.

It just does not look like much. There is no dramatic swarm, no ball won in the final third, nothing for the montage. Some of the most impressive defensive work I have watched consisted of ten men shuffling five yards to the left in unison for forty minutes while nothing happened. Nothing happening was the achievement.