The big thing that attracts bums on seats for the DUB routes are the 2 aspects:
1) a PROPER hub carrier. Yes yes, we have the flybe hub, but, with capacity limited to a dash 8 in the majority of cases, with a smattering of E175 or E195, one wonders how affective this is. Passengers may not understand the benefits of starting the journey on flybe at say ABZ to then get on a Virgin Atlantic flight at Manchester.
Aer Lingus as a seamless through experience of one airline all the way though, with a better transfer process and much easier for passengers, so does have the edge in that respect.
Also, Ireland has a huge inbound tourism and VFR market in the summer that really shouldn't be under estimated.
It would be beneficial if MAN could really tap into the Lake District market as the Americans love that sort of thing, but in time maybe it will take off (pardon the pun).