Article writing vs adding more content for improved ranking position?

I have dutifully written articles and submitted them to ezine and GoArticles without much of any movement in the sites I have targeted with them. I am talking about over the course of almost a month.

But, I have noticed that if I add more quality content to the sites, I mean text content that Google loves to chew on, they move up little by little.

One site that started around 22 is now at position 11 and even made it to 10 earlier today. Another one that started out at 53 has made it up as high as 12.

The biggest jumps in ranking have coincided with rewriting the content (that was written by someone else) to be much better quality.

To be sure all the sites I am working on have varied a bit in position but hardly ever more than just a few positions either up or down.

But in all cases it seems that quality content has had a bigger impact on the rankings than any number of ezine type articles.

I was discussing the use of ezine articles on Google's Webmaster Forum and they said that Google pretty much ignores backlinks from such articles these days.

I am inclined of course to not believe everything I am told on Google's forum but my own experience has led me to believe that there might be something to that.

Has anyone else noticed this? Where ezine articles don't seem to do much of anything at all with respect to obtaining an improvement in ranking? Vs just putting up more content and quality content at that?

I do not mean to say that ezine articles are entirely worthless. I believe they ARE good for syndication (I've change my mind on their value for this from an initial stand against it) and for speeding up an initial indexing but they don't seem to be very good for ranking purposes.

Has anyone else experienced this kind of thing? Just curious.

Carlos