The Economic Theory of Human Capital - theoretical explanation for the skill-unemployment relationship

Using Human Capital theory (Becker, others), explain the relationship between skill and unemployment.

Naturally, economists and the public at large usually think of skill-level having having an inverse relationship with unemployment. But you should be able to describe why this is, put it into terms of Human Capital, and perhaps think of some exceptions to the general relationship. This can be conceptualized on both macro and micro levels