So, I run a northeast skiing forum, AlpineZone.com.
The site has been up for 13 years (!). This past summer, I undertook a massive site redesign, which went live I believe in July. Essentially, there are two "parts" to the site; what i call the "Forum" side (via vBulletin, at forums.alpinezone.com) and the "Content" side, which used to just be HTML / Includes but is now on a CMS with a custom theme to match the look across the site.
The "Content" side used to be split into various subdomains ... so there was skiing.alpinzone.com, hiking.alpinezone.com, etc. When the site was redone, all of these just went into subdirectories instead - so alpinezone.com/skiing/ alpinezone.com/hiking/ etc.
I wrote most of the redirects myself, but had difficulty with some of them.
Also, I made the front end of the content site dynamic by using RSS feeds from various areas of the site to aggregate what's new on the home page. This worsk well but I noticed that each RSS entry was creating a duplicate entry on the CMS, instead of just linking to the original content. So; I set all these to NOFOLLOW.
The above chart is from Webmaster Tools. You can see that change I made around 12/15, where the "Not Selected" drops like a brick.
I'm wondering why my indexed pages seems to be suffering so bad. I have noticed traffic on my forums is way up since the redesign, but "content" traffic is down, by about 20%, and I'm trying to recoup and understand if this is a result of the changes I made. I had some SEO help from oDesk but it wasn't really that great, I still had to go back and readjust all of my redirects , title tags, and meta snippets.
I''m definitely not an SEO pro so any advice or where I should look next would be appreciated. Thanks!