the French staff literally thought a substantial armored force couldn't go through the Ardennes. they ignored intelligence giving them advanced warning because it was not a possibility and the scouts mustve been mistaken. they could've moved more troops to counter, attacked them aerially/conventionally in the forest, but their rigid understanding of the combat theater blinded them until it was too late.

i wouldn't necessarily call it an 'outdated command structure' but poor leadership & strategic inflexibility in spades