Mundy,
You're well off the mark on the success ratio. On some days it is as high as 50%.
Everybody who gets an invite to The Rivers has the chance of a job. There are some excellent people who come to selection, unfortunately, there are also a few who think that BA owe them a job and come unprepared and sadly, there is a very small minority of people who shouldn't be allowed anywhere near an aircraft.
If you can't be bothered to prepare for selection, how much effort would you put into learning a new type and new SOPs? The job is there for you to lose!
PS. Each typo on your application will cost you a point!!!!