Zen and the art of competency measurement

It's not what you know that makes you an effective worker. It's how you understand your role that makes you effective.
In other words, says Professor Jorgen Sandberg, competence is not attribute- based, but understanding based.
Our understanding of what our work is would then inform our subsequent actions in that particular role.
The problem, Prof Sandberg says, in measuring competency via attributes is that it does not necessarily reflect the in-work performance of the individual.
In other words, just 'cos someone has skills doesn't mean he would use them effectively.
Don't look at competence from the outside, exhorts Prof Sandberg, look at it from the "inside". Don't divorce the attributes of a worker from the worker himself.
Of course, attributes are necessary -- a doctor still needs to study medicine (and pass his exams!) to be a doctor. The question here is: "What makes one doctor better in his job than another doctor in his job?"
And here's the bad news: There is no one single answer to that.
Thoughts?