I’ve always found the BA recruitment process a little bit strange tbh. Very set in their ways, I feel there is no scope for example saying “well he didn’t have the best interview, but he seems like a nice guy so lets see how he gets on in the sim”.
I remember running into a guy who was once in the holding pool for them, ended up drowning. Applied again and didn’t get through the interview, seems to make little sense to me.
That said, my initial airline had an incredibly long winded recruitment process and I saw loads of good guys get canned during that process also. I think like most things, if comes down to how you feel on that particular day and a large degree of luck of the draw in relation to interviewers and sim checkers etc.