Here is an excellent article I co-wrote, primarily as a researcher and provider of facts, and editor, with Jack Thornton (a splendid technical writer).

Imbued with a few of my favorite key phrases (i.e. "bleeding edge", etc.) this article does attempt to encompass, and indeed manages to capture, the complexities of Technical Search (not only in Mechanical Engineering, but in multiple other fields, as well).

In my experience, the goal of a Search is almost always to identify candidates with a rare multiplicity of skills -- typically great "hands-on" talent, accompanied by skills at management, leadership, and communications (i.e. sales and marketing).  This "niche" -- of the multimath, polymath, multi-talent, or whatever you choose to call it, has been a standard part of my repertoire for several decades.

So, if you will, and if you desire, please read this article from 2013:  https://www.academia.edu/7950689/_To_a_T_