Every piece in this series so far has had the same blind spot, and it is time to admit it. A goal-difficulty methodology measures goals. It cannot see the player whose entire value is preventing them. The best young player at this World Cup might be exactly that player, and the model that runs this series would never find him.
His name is Pau Cubarsí, he is a center back, he is already a Spain starter at an age when most defenders are years from senior football, and the difficulty methodology cannot rank him at all.
The blind spot, stated honestly
The methodology scores the difficulty of a shot at the moment of contact. Shot location, defensive pressure, keeper position, body part, obstructed vision. Every input assumes the action being measured is an attempt to score.
A defender's hardest actions are the inverse. The recovery sprint that erases a counterattack. The body position that turns a striker onto his weaker side. The interception read three seconds before the pass is played. None of these appear in a goals dataset, because none of them are goals.
Why Cubarsí is the sharpest example
Cubarsí ranks second among all teenagers in the CIES potential model, behind only Yamal and ahead of every attacker except him. A center back rating that high that young is close to unprecedented, and it is built on exactly the actions the goal-difficulty model cannot see.
He defends with anticipation rather than recovery, which is the rarest and most valuable defensive trait. He steps into passing lanes Spain's system depends on him reading. He defends enormous space behind a high line, which is the most difficult defensive assignment in modern football.
What the World Cup format does to defenders
The forty-eight-team format is going to expose defenses repeatedly to a specific stress. Underdog teams sitting deep, absorbing pressure, then springing fast direct counterattacks into the space behind high lines. That counterattacking transition is the single hardest situation a young center back can face.
The point of admitting the blind spot
The best young player of World Cup 2026 might be Yamal, and the model can prove it. Or it might be Cubarsí, and the model would never know. Watch the defender nobody is clipping. The most important young player of the summer may be the one whose best moments leave no highlight at all.