There could be several reasons for this. First it's impossible to know exactly why without knowing the keywords your using, but lets assume they are very attainable since the post ones are already ranking well…

My first thought is that the ones in the posts are ranking well because they are linked to from your main page. I'm just taking a stab in the dark here, but maybe you could do some article marketing for the three keywords on your static page to give them some seo boost. That will probably also help out the post pages they are linked to as well!

Be very careful and take your time with article marketing… craft useful and high quality articles about the subject that your keywords deal with. In fact to be safe I would make three separate articles, each dealing with 1 keyword at a time and each being 100% natural (not spun) and unique. Post them in different article directories of high quality and page rank.

Also make sure you have social signals and activity going on all of your pages if you haven't done so already…

Hope this helps a little!