The overlap that nobody uses is still doing work

A full back who runs outside and never receives the ball has not wasted the sprint; he has moved the only defender who mattered.

There is a certain kind of supporter who groans every time a full back overlaps and does not get the pass. I understand the instinct. Sixty metres of running for nothing looks like waste. It is not nothing, and the reason is the defender who had to make a decision about him.

The mechanism is about eyes rather than space. A full back tracking an overlapping runner has to keep some fraction of his attention on a player behind and outside him. The moment he glances, the winger in front of him gets a free half yard to attack the inside. That half yard is the whole point. It is why the overlap works best when it is not used, because a run that always ends in a pass is a run the defender can eventually ignore in favour of jumping the ball.

Which sets up the more interesting question of when to actually deliver it. My rule of thumb, argue with it if you like, is that the overlap should be used often enough to stay credible and no more. Perhaps one in four. Any more and you are playing a predictable width game. Any less and the defender stops respecting it, quite rationally, and starts pressing the winger with everything he has.

The underlap has become fashionable partly because it solves the credibility problem from the other side. A run inside the winger threatens the space between centre back and full back, which is the space nobody wants to defend because it belongs to both of them and therefore to neither. But underlaps are expensive. They pull your full back into a central area, which wrecks your rest defence if the move breaks down, and they need a winger who can hold the ball long enough for the run to develop.

Here is my actual complaint. Teams have got very good at the geometry of these runs and quite bad at the timing. An overlap that starts too early arrives before the winger has engaged his man and simply gives the defence a spare body to pick up. An overlap that starts as the winger takes his first touch inside is nearly unstoppable.

Same run. Same player. Two seconds apart. One of them is a chance and the other is a groan from the stand.