In my many years of interviewing sysadmin candidates, the most important qualification, and the hardest to explain in terms that make sense to HR, has been “do they think right?”. The core of it, I think, is the attitude with which they approach diagnosing and solving problems.
Behavioral interviewing techniques can produce some useful information about problems they’ve dealt with in the past, but not so much on how they really got from X to Y. HR gets very nervous if you do anything that even looks like a direct test of an applicant’s abilities, so the best approach I’ve found is to swap problem-solving stories and pay close attention not only to the ones they choose to tell, but to the things they say about mine.
I don’t care what, if any, degree you’ve got. I don’t care who you’ve worked for, who you know, what certification programs you’ve completed, or how precisely your last job matched our current requirements. If you think right, and you’re not a complete idiot, I can work with you.
The two people who’ve been hired to replace the five of us are not complete idiots. One of them shows signs of thinking right.