Grammar vs. Library.
A library is a set of moves a player can retrieve when the situation matches one. A grammar is a generative system that produces a move the situation requires, including moves the player has never used before. Library is retrieval. Grammar is generation.
Most American academy coaching installs library. Drilled patterns. Half-turn on the back foot. Body shape. The two-touch combination. Each of these is a stored move that fires when a situation matches it.
Library coaching works for ordinary situations. Most situations in a soccer game are ordinary. A library player plays competent soccer at every level he encounters for years.
Grammar is harder to install and almost never taught directly. A grammar player has not memorized more moves. He has internalized the structure that produces moves. When a situation arrives that does not match any stored pattern, the library player has nothing. The grammar player generates something new.
This is what people are reaching for when they say a kid is a natural. They are watching grammar. They mistake it for genius. It is not genius. It is a different kind of acquisition.
Grammar is installed by years of unstructured play against varied opposition. Pickup with adults. Pickup with kids who play differently. Tight spaces. Bad surfaces. Situations the coaching curriculum did not anticipate. The grammar gets built by being forced, repeatedly, to produce something the library does not contain.
An academy can install library in twelve weeks. Grammar takes years and cannot be scheduled.