The Perils of Metrics

Metrics are used to answer questions, and questions are like fleas:

So, naturalists observe, a flea

Has smaller fleas that on him prey;

And these have smaller still to bite 'em,

And so proceed ad infinitum.

(Jonathan Swift, On Poetry:  A Rhapsody, 1733)

So a change in a single metric should be assessed both in the context of other metrics that address the same question, but also in the context of other peer subquestions that address a wider issue.  If the wider focus is not maintained, well, "... one little old metric goes down, and everyone loses their minds!". 

Here's an excellent example from one of my favorite financial markets commentators.

http://www.capitalspectator.com/dont-confuse-manufacturing-with-the-broad-macro-trend/