Permalink structure changed
When I first setup this blog 2 years ago, I went with the default permalink structure in Wordpress. All the new blogs I helped configure I went with a more readable and SEO-friendly permalink setup. I didn’t change mine because of existing incoming links and also if 2 URLs go to the same content Google ranking will drop significantly. I looked into an easy way to do a 301 redirect and found a permalink migration plugin, it’s pretty awesome and does exactly what I wanted (301-redirect old permalink to the new structure). Now the URLs look a lot better, instead of the post ID I have the date and the post title in the URLs. 
