I was very surprised that DUB was so much busier trans atlantic than the likes of CPH, MAN
Its no surprise DUB was bigger than MAN for Trans-Atlantic capacity
For DUB, large inbound market, especially over summer, home based hub carrier, pre-clearance, lower taxes and of course, DUB is a European Capital.
MAN has only little of the first advantage, and none of the other advantages DUB has. Add to that, MAN has to deal with the fact LHR is only 200 odd miles away, with connections by air, road and rail
However, despite those advantages, MAN still gives a good fight, with around 130 each way departures to around 18 trans-Atlantic points.