viral - 11:38 pm on Jul 14, 2013 (gmt 0)
It has nothing to do with the length of your articles. Quite frankly you are being beaton by sites that have more authority than yours for whatever reason. For example if the Huffington post decided to target your keywords they could summarize your articles for $5 and be beating you within 24 hours. Unfortunately that is where we are today with Google. If a sites "brand signal" (whatever that may entail) is better than yours and content is close to yours, they will beat you end of story.
Bill Slawski wrote an article on this a little while ago. Google actually has a patent for it. What Google is doing is finding what they consider a "trust worthy" source for content. They really don't care who the originator is as long as some site that they trust puts it up then they will display it.
I may be wrong but your site is probably suffering from this affect. We have seen scrapper sites do well from this. They fool Google into thinking they have some kind of trust factor or brand signal and they take your content and beat you with it.
The problem is that Google appears to be heading down this road more and more. After all Eric Schmidt said "Brands are the solution, not the problem," Mr. Schmidt said. "Brands are how you sort out the cesspool."