The most important thing to remember is that BE don't do anything for nothing and they aren't going to base any aircraft anywhere but their current bases.
All services wherever they may fly to, will centre around these bases and nothing else.
Certain airport authorities have been wildly optomistic about potential passenger throughput on certain routes and, whilst some may say they were sucked in to believing what they were promised, common sense would tell the most naive airport director that some routes work and some don't.
Basically, any route to a destination which is popular with second home owners, if marketed correctly, should work year round, its just a question of getting the right airline which can be assured of at least 90% capacity in the Summer and around 75% the rest of the time.
A bit of clever planning would see BE's nose put out of joint in the Winter, but sadly, too few airport marketing teams have the nouse to put that together.