[toomuchcoffee]

Also, many of these "disaster" cases may simply be suffering from an unfortunate, but all too human cases of stage fright, especially if it's their first F2F at a big company like Apple. Some people just freeze up involuntarily, and trip all over their tongues when being grilled by people they look up to and respect. They're human beings, not quiz-answering machines, after all.

Not that we need to slow down and make some kind of special accommodation when this happens -- because indeed, such episodes may fairly be viewed as signs of a lack of experience and confidence.

But it still surprises me how often people fail to see the basic humanity at play in these situations: instead of thinking "poor guy, he seemed really nervous", all that comes to mind is "What a loser! He couldn't solve that Euler problem with me staring and grinning impatiently at him the whole time. How did he ever make it through the phone screen?"

[jfb]

"Also, many of these "disaster" cases may simply be suffering from an unfortunate, but all too human cases of stage fright, especially if it's their first F2F at a big company like Apple."

This is absolutely correct, and there's no hard and fast set of rules to determine if performance in a staged, artificial environment like an interview correlates in any significant way with performance at the job intended. There're a whole host of issues around hiring in particular and coping with humans in general that the tech industry does an astonishingly bad job with.

To me, the goal of interviewing is not to find someone who is a clone of someone who already is on the team, but rather to find someone who brings different and useful perspectives to the job. If they can work on existing problems day one, so much the better, but if they can never get beyond working on existing problems, then they were a mis-hire.