Airflow is a combination of many things:
Vent flow area
Fan's ability to over come the resistance of the above
What is behind fan; like HDD cage, cables, etc.
Direction of airflow
Exhaust placement and restrictions.
Most modern aircooled cases do not address the huge amount of heat coming off of modern GPUs .. especially in regard to exhausting that heat without it mixing with cool intake air and feed warmer air to CPU cooler .. and...