Employers taking longer than ever to fill positions

Just ran across this WP blogpost by Catherine Rampell that shows the average vacant job stays open 25 days.  There is tremendous variance by industry.  Construction positions are filled within 10 days, whereas finance positions take 40.  Want a good example of diseconomies of scale?  Firms with 5000 or more employees take 68 days!   

Vacancies are at the highest level in the history of this since data series that goes back to 2001.  One might interpret this as another sign that the labor market is tightening, although this is inconsistent with the extremely modest wage growth we are observing.  Another interpretation I am seeing is that corporate America has unrealistic expectations of job applicants and would rather invest in finding the ideal person than train someone else.  This might be a rational strategy at a time when employment still does not seem to be growing very much.