@EI-BUD AMS was a flight that operated twice daily during the worst of the post-2007 recessions. It still operates more frequently in Winter than in Summer. A conspiracy theorist would put the reduction down to IAG trying to avoid connecting pax using AMS; a more reasonable explanation is that there is more money flying to Malaga or Faro in the summer months. There's really no other way to describe what has happened with the schedule in recent years other than messing around with it. Considering it's the second most business pax heavy route at Cork and accommodates a lot of frequent flyers, it could be seen as short-sighted.
While I fully accept that Aer Lingus don't have the flexibility that Ryanair do to create capacity with aircraft based in remote airports, the fact is that beyond sweating the based aircraft more and more, there has been no real EI expansion at Cork for a long time. At this point those aircraft have no more to give in the summer schedule. The appearance of Air France/KLM and to an extent Swiss at the airport speaks of a connecting passenger market that was being inadequately served. If the gamble was that everyone would use an Aer Lingus flight to Heathrow or a bus to Dublin for an Aer Lingus flight from there, it would seem to have gone wrong.