>There is statistical data saying the opposite

Interesting study and really good discussion on HN at the time, but the opposite of "[Whiteboard interviews] often give a very good and reasonable signal that often has a high corollary to work performance" would be something like "People who do well at whiteboard interviews tend to be worse performers at work." I don't think that's what the study said at all; rather that people do worse at whiteboard problems when they're being watched vs. not being watched.