Placing someone at mid / senior / junior is not "cocky"... it's pretty subjective if you do it right. The guy missed questions that over 50% of our applicants knew the answers to.
I'm not talking the "implement this obscure algorithm from scratch on a whiteboard" kind of question HN is so fond of. The hardest coding question we ask is Fizz-Buzz.
But we can't / won't pay him more than we pay other employees with similar or higher skill sets.
If we drew a bell curve of all the applicants we had, this guy would be in the middle.
His resume was impressive though. My guess is the company that hired him didn't do their diligence and only weighed the resume.