Content without analysis is meaningless. It's just a bunch of words about a topic. Given that the purpose of content marketing is to provide valuable content to your prospective customers in order to drive customer actions, it's important to measure the response against the actions you thought you would receive and determine if your content needs to change, increase or decrease.
The four areas the article author, Uri, points out are as follows with my own definitions:
Message - what you're presenting
Format - how your presenting it
Distribution Channel - where you're presenting it
Promotion - how your giving attention to what you're presenting
Each of these afford you the ability to perform what I call "Testm Measure, Improve" (I talked a little about this recently). You can test a change in each of these components (for example, the format can switch from something closer to a boring data sheet to a more exciting infographic), measure the result, and if it is bring you better conversions, keep that improvement and move onto the next change (which, remember, can still be within the same component - there isn't just one thing wrong with your execution!).
Now, Uri lists various metrics for each component. I believe you should focus instead on whether each of the components is pushing a customer through your defined customer journey. That is, instead of, say, measuring return visitors, you measure whether making a change in format or message is causing the customer to perform the action you want them to take next.