Realize though, that the pool of people actively applying to jobs is, on average, FAR worse than the total population. Even companies who are pretty bad at hiring can make some kind of selection for quality, and great engineers get fired way less than terrible engineers, so in theory, the very worst engineers in the world would continually apply for jobs and never be hired, or would be quickly fired.
My experience suggests that it's very rare to get a superstar from any passive method (that finds active job seekers). That pool is just to dilute with talent. To get the strong candidates, you have to be active (to have a shot at the passive candidates) or extremely lucky.
It's no surprise to find only 1 in 100 of unemployed engineers are truly good. If you just post openings, you're unlikely to interview even a representative sample of the population, let alone an above-average sample.