Hiring people comes with a high degree of risk. That is why you have a probation. Reading code is also risky. I usually forget why I did what I did and more often than I would like to admit the BLAME is mine - a resignated "..who wrote this?" often turns into - a-ha, it was me.

Resumes is good in the same way grades are good. They might get you to the interview, so don't knock it down just yet.

The hard skills are absolutely important! But the soft skills are equally so. When you talk to your candidate your first impression will be the most important indicator on wheter you will be able to endure working on varieties of task in the immediate future and far away future.

My favorite soft metric is to take them to lunch and observe how we can interact, talk and <sic> hygiene.