On a counter-attack the ball carrier is rarely the player who creates the chance. What decides the outcome is where his teammates run, and the useful runs are the ones that move away from him.
Converging runs let one defender cover two attackers
When supporting players drift towards the ball, the attackers end up close together and a single defender can position himself between them.
That defender no longer has to choose. He can block the pass and still be near enough to challenge the carrier, which turns a numerical advantage into an even contest.
Separation forces the choice back onto the defence, because a defender cannot occupy two lanes that are ten metres apart.
Width stretches a retreating defence horizontally
A defence running towards its own goal is compact by default, since every player is heading for the same area in front of the goalkeeper.
A wide runner obliges one of them to break away from that group, and the gap he leaves is the passing lane the carrier is looking for.
This is why wingers on a counter frequently stay near the touchline until the last moment rather than cutting inside early.
The run beyond is the most valuable and the most wasted
A player sprinting past the last defender is the only run that threatens the space behind, and it is the one defenders most fear.
It is also the run most often ignored, because the carrier is watching the ball and the runner is behind his field of vision by the time the pass is available.
Teams solve this with a rule rather than a judgement: the run beyond is made regardless, and the carrier looks for it first before considering anything else.
Somebody has to stay behind the ball
A counter with every attacker committed leaves nothing if possession is lost on the edge of the area, which is where most counters end.
The trailing runner, usually a midfielder arriving late, serves two purposes: he is an option for a cutback and he is the first line of defence if the move breaks down.
Because his position is the same in both cases, the role costs nothing, which is why it appears in almost every well-organised counter-attacking team.
Timing separates a run from an offside
Runs made too early are caught offside or force the carrier into a pass he is not ready to play.
The correction is to time the movement to the carrier's head position rather than to the ball, starting as he lifts his eyes rather than as he receives.
Coaches drill this as a shared cue, because a counter-attack collapses just as easily through a run made half a second early as through one made too late.