I think the problem with BA's cabin crew IS and HAS been consistancy.
In the last 10 years that I have been within the industry, the airlines I have primarily flown have been Emirates and BA (with a little bit of Etihad and BMI on occasion).
What I have found with EK is that they are far more consistantly good. The crew generally seem fresh, enthusiastic, and eager. On the other hand with BA, I find it quite frustrating, in terms of consistancy; when I fly, to quote Forrest Gump "...is like a box of chocolates, you never know what you gonna get". I have had flights where the service has been outstanding, and I really wish that will be the case the next time I travel. But then I unfortunately find I'm on more flights where I have been less than impressed.
But this is the problem for BA that they urgently need to rectify; firstly distnguishing the deadwood from the good crew. And secondly, getting rid of this deadwood!