"Good enough" methods get you "good enough" people.
Thanks to the slow move toward professionalisation of BAs, and the profusion of interview question coaching sites around most people with a decent memory and half a brain won't have any trouble answering the "good" questions.
Any schmuck with Google and time on their hands to know the answers, even to the behavioral questions. Examples are below:
"Great" questions for "great" people
For great people you have to go to a completely different level of question. Ones with no "right" answer and lots of scope for follow on questions.
A lot of these are the classic "Microsoft" questions, such as "How would you move Mount Fuji?", "Why is a kidney dish shaped that way?", "What's the best requirement you've even heard?", "My business needs a CRMs - what would you suggest?"
Based on how they response you see if they can:
Which happen to be all the things that separate good and great BAs.
I've got one question that's a semi-mathematical logic puzzle - but we force people to give their answer on the white board without using words or number. This will tell you in under twenty seconds if someone can put together the explanatory diagram that are so important to any Snr BA or Business Arch.
If you have the time - roleplay
I love to roleplay BA scenarios. Taking a small problem from elicitation, through design, getting interviewees to practice specific skills (Interviewing, use cases, data models, process models, test design, change management, as you go.)
Problem is is takes forever. Half a day is about the shortest amount of time you can do anything useful in.
Lets face it, go with gut
Sometimes you just know within the first five minutes. Really great BAs have a certain way of engaging with people, keeping conversation going, making sure they understand what you say, and being generally empathic while logically rigorous that's just obvious during a short conversation.
We've hired people who completely flunked the BA method and skills questions but just gave such awesome interactions during our puzzle section that we know there was something there. Every one of these people has turned out to be a high-performed with just a little bit of mentoring.
On the flip side I've seen people hired who absolutely nailed the BA method and behavioral questions - but who flunked the puzzle section. They're invariably been low performers (for their years of experience) who mechanically replay the same methods, tactics, and ideas year after year. Not a lot of value-add,. Classic case of people having 15 years of experience, but its the same year 15 times over. Great for domain experts - lousy as business analysts.
P.S. All the examples I've listed here are our second-class questions. I'm not sharing out our best ones unless you're looking for a job :).