In my experience, I've seen some incredibly smart people (the kind who ace those brain teasers) make some incredibly bad technical gaffs.

Like an architect who chose synchronous HTTP as a protocol for a service that later required the ability to cancel long running operations in progress (he unfortunately didn't realize why hitting the browser stop button wasn't the same as cancelling the process on the server).

Or a senior dev who thought that a JSP scriptlet getting the current time would show the client's time, instead of the server's time.

There is no guarantee that people who ace brain teasers will necessarily be able to figure out technical issues, although they are often excellent at sounding like they have figured out technical issues when they leave the details for the people who get the real work done.