Their error was reinventing it literally every couple of months, without letting it 'settle'. As a result the reader's never really knew what to expect, so it lost it's regulars, and failed to attract any new blood, hence why it's dying on its arse. They clearly panicked whenever they got the sales figures through and thought "Shit, that hasn't worked, let's try something else".

There are a bunch of factors that have erroded their market, but most of them are their own doing!