Two teams listed in the same formation can produce games that share almost nothing. The notation captures the least important part of a system.
Distances do more work than positions
The same shape can be played with fifteen yards between lines or thirty, and the two versions defend completely different areas. Compactness is a separate variable from formation.
A compact block concedes space in wide and deep areas but denies central passes, while a stretched one covers more of the field and can be played through. Neither is visible in the notation.
Coaches spend far more training time on these distances than on the shape itself. The shape is the easy part to install.
Triggers decide when the system activates
Every defensive scheme includes moments that start the press, such as a backward pass, a heavy touch or a ball into a wide area. Which moments are chosen defines the team.
Two teams with identical shapes and different triggers will win the ball in different parts of the field. That changes where attacks begin and therefore what the attack looks like.
A team with no agreed triggers presses individually and inconsistently, which produces the appearance of a system with none of the benefit. The shape is intact and empty.
The same positions can hold opposite instructions
A wide midfielder in one team is told to hold width and stay high, and in another to tuck inside and support the midfield. The team sheet reads the same both times.
Fullback instructions vary even more, ranging from overlapping to inverting into midfield to remaining in a back three. Each produces a different team.
These are the choices that determine where a team's numerical advantages occur. Formation notation predicts none of them.
Tempo is a separate design decision
How quickly a team plays forward after winning the ball is chosen, not inherited from the shape. A possession team and a counter-attacking team can share a formation.
Tempo also varies within a match by design, with teams slowing deliberately to protect a lead or accelerating against a disorganized opponent. That control is a taught skill.
Two teams in the same system with opposite tempo settings will not resemble each other in any respect a viewer would notice. The similarity is on paper only.
What to look at instead
The useful questions are where the team wins the ball, how many players it commits ahead of the ball, and how far apart its lines sit. Those three answers describe a team.
Formation is still worth knowing because it identifies who is responsible for which space. It is a starting reference, not a description of play.
Treating it as more than that is why so many tactical arguments are about the wrong thing. The numbers were never the system.