A sending off forces a team to remove one job from its structure, and the choice of which job determines everything that follows. There is no shape that covers the field with ten.
The decision is which line loses a player
A team can take the missing player from the forward line, the midfield or the defense, and each choice creates a different problem. Coaches decide by what they need from the remaining time.
Removing a forward preserves defensive structure and leaves the team with almost no outlet, so possession cannot be held. The ball comes straight back.
Removing a midfielder keeps the outlet and concedes control of the center, which is where a team with an extra player will attack. Both costs are real.
The common answer is a flat block of four and four
Two banks of four with a single forward is the most frequent ten-man shape because it covers width in both lines and requires little communication. Its virtue is simplicity.
The weakness is the space in front of the defense, since there is no player screening it. The opponent's central midfielders receive freely.
Teams accept that because shots from that area are lower value than crosses into an unprotected box. The structure chooses which chance to concede.
Score and time change the calculation
A team ahead late will drop deeper and narrower, accepting territory to protect the goal, because it needs only to survive. Retaining an outlet matters less.
A team behind cannot do that, since it must eventually attack and needs someone to receive the ball. It will keep a forward and defend with a smaller block.
An early red card requires a different answer again, since a long period with no possession is not survivable. Teams keep more attacking structure than the situation seems to justify.
The extra player is used in a specific way
A team with eleven against ten usually creates the advantage in a wide area rather than centrally, because the ten-man block is narrower. The free player is a fullback or winger.
Attacking teams also circulate the ball more slowly to move the block sideways, since a compact block is easier to break by shifting than by penetrating. Patience is the effective approach.
Ten-man teams therefore defend by controlling how far they are made to travel. Refusing to chase the ball across the field is the core discipline.
Why some ten-man teams improve
A sending off simplifies a team's job, removing ambiguity about whether to press or hold. Everyone knows the answer, and the block becomes more coherent.
It also removes the opponent's fear of the counter-attack more slowly than it removes the counter-attack itself, so space behind the advancing team can persist. One forward and a long ball remain live.
That is why the ten-man goal on a break is a recurring event rather than a fluke. The structure of the situation produces it.