Cork, unlike Shannon and Knock actually has a large population to serve and should be doing a lot better but continues to under-perform as its management is the Dublin Airport Authority who are focused on furthering the success of Dublin airport.
Population of Cork County - 519,000
Population of Connacht - 542,000
Other than Cork having a city on its doorstep there isn't too much difference between the catchment of Cork and, as an example, IWAK. Is the idea that Cork has a huge population to serve not somewhat overstated? The city is close but the county is larger and more spread out than any in Ireland, it is almost provincial in terms of size.