Lottery!
It is exactly what was written about KAL here: it's just a big lottery.
It's not about your abilities, experience level, airmanship etc. It depends only on the mood of the clown of the day, if their kimmchy was good or not.
Too sad an otherwise good airline still empowers some really sick bastards to judge who's good or not for them. I know about at least 10 excellent professionals, with all possible credentials on experience, instructors, checkairmen etc that bozos failed for nothing, while guys below average passed and are happy (?) there.
My recomendation is: do not risk your present job for an outfit like this, or, at the best, take a leave of abscence if you really want to try.
They are not serious.