Selecting the "best" person is very difficult. I went through it myself and was sometimes in error.

We can only do the best we can do. We need to honestly evaluate the person and how they appear, act and answer. Too pat is not good. Neither is stumbling to answer. Kind of like the Goldilocks, just right person.

Even then, how they perform can be totally different than how they interview. The best we can do is to take our best shot. Then, see what our selection does. If they make it, great. If not, correct our mistake and find another. Not sure there is any sure fire way to do different. If there is I would love to hear it.