The 'decline' at MAN is mainly attributes to the cut in frequency, overall load factor is still good.
Yeah they raised capacity to twice daily (by pulling LGW) which was unsustainable, for an airline that is essentially a projection of political power. 1-0 Emirates I would say.
but I know the number of passengers that flew with BA between MAN and London's two largest airports went down with at least 11 740 passengers in April.
Um wouldn't that be attributable to BA dropping MAN-LGW?
As for Little Red what do you want? Would you like BA and VS to compete against each other to their respective hubs at LHR or have no VS domestic at all? They're not in a position to make money on MAN-JFK so it's a good opportunity to keep Flying Club members happy, keep jobs in the UK (OK, Ireland for the moment) and keep BA on their toes.