Someone with a PhD has an academic background and great technical depth — they should be a shoo-in for an instructor role, right? Alas, no. In fact, when interviewing, I treat a PhD as a yellow flag.
This is not to say that a PhD is in itself a bad thing — I have one, several of my colleagues have one, and an equal number of my colleagues started but did not finish their PhDs. Even so, I have observed that the number of people with PhDs that make it through the recruitment process is relatively low.
How can this be? Sometimes it is due to surprisingly weak depth in the technology they wish to teach. They may have used the technology to support their research area, but they didn’t learn that technology in the necessary depth to teach it.
However, the most common reason for passing over someone with a PhD is if they can’t explain a concept in simple, straightforward terms.
I once overheard the following comment between two attendees after a training session I was in (not running!) — “That guy’s a genius! I didn’t understand a word they were saying”. This is not the reaction you want from attendees. An instructor’s job, when done well, is met with the rather unimpressive “That’s obvious”, or “I get it now, is that all it was?”. You might be lucky and get a more emotional response of “Why the @?%^ did no-one explain it like that before?“.
It can be hard to remember what it’s like to approach a topic for the first time, and that is especially true for PhDs steeped in a topic or technology that has become second nature.
None of this is to say that having a PhD is bad, just when interviewing the interviewer must ensure that the candidate is capable of clear, simple expression.
Is there ever a time when having a PhD necessarily adds value to training? Yes — sometimes it can help establish technical authority. When training a group with academic backgrounds it can also help that the instructor has been in that environment previously.
All successful candidates must demonstrate the ability to express themselves clearly, and in terms suited to the audience. Be sure that your PhD candidate can do so.