there could be an easier case to debug, where CBD cargo is not growing to it's potential as it should.
In GW3 I have a lot of routes from Denver to China, so simple-simple CBD. Yet despite the flights being there for years on many routes cargo has NOT grown to it's potential, as it does in lots of other places. Seems a problem specific to Denver. Now being Denver, there aren't any competing flights to China from nearby airports. So this could be a less complex scenario to debug why CBD is failing..
Simon