I understand what you mean by rigor but I'm not sure that your quest for rigor in that sense would yield better results. I could be very wrong, of course, my experience is nothing but a relatively small list of anecdotes. But if you indeed have a rigorous way of assessing candidates, I certainly look forward for you to creating the best recruiting agency ever, becoming a billionaire and transforming this field forever (not being sarcastic, btw, I'd like so see some innovation in this field, I'm just not sure how "rigorous" can work here, but if you do - I hope you are right and I am wrong).