Here's a wild ass idea: have you engineers do all the resume reviews, screening calls, and interviews. Leave HR and most of management entirely out of it.

Then just hire people who can intelligently speak to a relevant resume, and who get along well with your group. If they don't work out, fire them.

People spend entirely too much time obsessing over how to hire people, usually mumbling some nonsense about how they'll destroy their team or be sued out of existence by a bad hire. Personally, I think it's a combination of desperation to cover one's own ass at all costs, and providing an illusion of control. If they'd focus on improving the workplace and their own communication rather than fretting about voodoo hiring theory, they'd be much better off.