I've witnessed some very strange results from BA selections amongst the F.Os where I work, good solid people get rejected and others who scrapped along the bottom standards of both technical and non technical skills were taken. I believe that the BA system is as inaccurate a method of selection as any other airline that has allowed HR to interfere.
I haven't applied my self, so have no first hand knowledge of the tests and procedures but the stuff described by colleagues doesn't seem to me to be suitable for selecting aircrew.