I would put it at 60:40 slot sit:rte evaluation
As above BA would have taken the easy option if all they wanted to do was slot sit and run an odd extra EDI/MAN/GLA etc which is indeed what they were doing in the Summer.
They acquired BMI complete with its fleet of 319's and need to do something useful with them for the foreseeable. They investigated potential routes and came up with LBA & RTM. RTM is doing better than LBA load wise but LBA does have 4 a day to fill (too many from a standing start IMO) and furthermore they started both at a terrible time.
BA have invested a fair amount in setting up the Leeds operation, time will tell if enough people back it. I'm unconvinced at the moment.
Some flights have nudged 100 pax but plenty are flying around with 30/40 on them. Fair enough it's been Christmas week but the operation seems robust an the figs need to improve in the NY.
One stat for you.... Saturday's early southbound had 95 pax and 72 were connecting to (primarily) LH services.
I think 3 per day in the summer could run well an avoi the dead 7am northbound loss maker too.