Sorry to jump in at the end here and not being a WSOp but a chopped WSO.
As far as I could see, each of the WSOp disciplines required different aptitude requirements and as such can be better assessed after practical application in the working environment.
I agree with the way it is now, although I can also understand the frustrations of people joining up to hang out the back end of a Chinook and then being told, sorry you are more suitable to throw sonar buoys out of the vomit comet and heat up ready meals.
I'm living proof that the aptitude test alone does not mean that you are suitable for a role.
I'll await the barrage of abuse (or should I call it opinion?).