[Comparable](http://docs.oracle.com/javase/7/docs/api/index.html?java/util/Comparator.html) is already loaded with meaning of ordering items.

Anyway - I think the current *Matchers are not bringing something essential. In terms of ability to compare:
 - the Diff (to be the new name of matchers) should be able to deal with comparing raw objects.
 - the labelling/reporting responsibility seems separate thing; and for now looks doesn't need to be pushed to that level (let invoker/consumer of diff deal with that).