Jake Barnes, who blogs at The Oilfield Expat, has a very good article about the perils of selecting managers from among the ranks of technical specialists. He writes in the context of the oil industry, but from my own work experience in the information technology field and in pastoral ministry, his words are appropriate for those disciplines as well. Here's an excerpt.
A lot of managers are former engineers or other junior staff who have shown technical competence or, more usually, served time or are of a certain age. The problem with this method of selecting managers is that it ignores the fact that management is more about personality than technical ability. Engineers tend to focus intently on details, and the better engineers do this more than the not-so-good ones. However, the latter often have a better grasp on the context in which calculations are taking place and a better appreciation of external factors not directly related to their own discipline, which is why most project engineers are former discipline engineers who found they either weren’t very good at calculations or got bored doing them.
What the oil industry rarely does is select youngsters who show signs of having a personality more suited to management than technical work – of which an ability to see the broader picture is but one of several – and assign them small, fairly trivial management tasks in order for them to gain experience in managing a process with the aim of achieving certain goals.
. . .
... experience is not required to manage something: competence is. But the oil industry is obsessed with a belief that management is something that must be earned only via strict technical competence or age, and as such denies its young employees the chance to hone their management skills on simple projects. Instead, they wait until they are approaching 50 before catapulting them into the Project Manager position on a nasty, brutal project in some seriously challenging environment like Kazakhstan and expect that they will learn and apply fundamental management concepts on their first try. Almost none of them do. Half of them were never suited to management anyway, and the half that might have been were never given the chance to learn in a more forgiving environment.
There's more at the link. I daresay most of my readers from a commercial or industrial background will find much to agree with.