Operational maturity describes how systematically an organisation runs and improves its operations — typically on a staircase from firefighting (everything is reactive) through reactive and visible operations to stable operations and continuous improvement, where the organisation improves itself.
The point of the model is the order: you cannot skip steps. Continuous improvement without stable operations collapses, because all energy goes to firefighting; advanced tools on an immature foundation become theatre.
Maturity is assessed on behaviour, not artefacts: not “do you have boards?” but “what happens when a number is red?”. The answer reveals the step more precisely than any self-declaration.