There’s no two ways about this, Google and the other search engines have their favourites. I’m sure you’ve seen it all before, either working for your client or evaluating your competition. There are a number of sites in every niche, whatever content they publish they rank well whether or not the content is optimised, has any inbound links and without really trying too hard.
You, on the other hand might have worked hard to rank for that content, have got some great natural links, lots of buzz but you’ve got little to show for it. What you don’t know is that these websites have managed to reach a high trust level with the search engines which helps their content rank highly.