Ryanair were expanding at the airport until 2008 but after the credit crunch and associated air recession they have continually retrenched.
The failure to open a base at Derry has been pivotal in the demise of the Ryanair operation. It lead to unsuitable schedules such as Stansted which necessitated being in the airport just after 5am which meant not only an even earlier start but all sorts of transport logistical problems so inevitably meant a stay at an expensive airport hotel.
Relying on spare aircraft from other destinations, such as Glasgow and Liverpool, also meant that flight times could differ from one day to the next due to the availability of aircraft and again weren't necessarily the best times to maximise demand.
The Alicante route had its season chopped and changed and eventually meant they didn't even operate in the peak months of August.
Then you gather your statistics and decide which routes are most profitable with no allowance for the mess that scheduling may have made.
Had Derry had its own aircraft it could have been a different story.
Blaming APD and then expanding at another airport with the same APD makes absolutely no sense.