It's something like the Peter Principle, wherein people are promoted to their level of incompetence and ergo an older large company is mostly staffed with people who can't do their job, but this one is less commonly cited. It's called something like "the XYZZY principle" as well, but maybe principle is the wrong word.
It says something like: most people (employees, companies, software) are good at normal tasks but all fail at rare or exceptional tasks, and then you find one that can do that rare task well, you'll mistakenly assume they can do the common things, too. But you'll be wrong.
This ranges from "the employee who can problem solve out of the box like no other can't seem to do time tracking well," to "this accounting software did charts better than anyone so we bought them, but found out they can't track simple sales orders the way all their competitors easily can".
I've run into this with careers and colleagues and companies, but I can't remember or find the name for it, though I know I've read it somewhere. Any ideas?
