The Prisoner's Dilemma is a two player game with one uncomfortable property: whatever the other side does, you personally do better by defecting, and yet if you both defect you both do worse than if you had both co-operated. Play it once and defection is simply correct. Play it repeatedly against the same opponent, and everything changes, because now they can respond to what you did last time.
On a pitch, a co-operative move is the patient one: hold the shape, contain the runner, compete for the ball without diving in. A defection is the press, the early challenge, the refusal to give an opponent a moment. Defecting wins the individual duel more often. It also breaks up the game, and a side that cannot build cannot score.
That is the trade the whole league is built on. Two co-operating sides produce open, high-scoring football and share the benefit. A defector against a naive opponent takes everything. Two defectors produce a scrappy hour in which neither of them gets anything, which is the mutual punishment outcome, and it looks exactly as bad as it sounds.
Each club here follows one rule, without exception, for the whole season. No manager overrides it, no result changes it, and no run of form softens it. That is what makes the table evidence rather than anecdote.
The numbers bear it out. A match turns on roughly 130 attacking sequences; the ones that reach the final third produce a chance, and a chance is worth what the expected goals say it is worth. Across a season the scores track the chances, which is why the table ends up describing the rules rather than the luck.