After merging two sites, one with ~40 URLs and one with ~700 URLs (due to a forum) the result was that overall traffic decreased by ~50%. I want to get the traffic back, as it was organic and a helpful resource to the community.
After finding this answer I decided to try removing the ~700 forum pages from the index by using a robots.txt disallow, which didn't work. As this FAQ and this answer point out, the robots.txt must allow the pages and meta noindex must be used.
After applying noindex tags to all forum pages, removing the disallows from robots.txt and waiting a week, still there are 700+ URLs in the index according to Google webmaster tools. However, if I view the advanced index status and check all the boxes, it shows 795 URLs indexed and 200+ blocked by robots. The blocked by robots graph line is increasing steadily (~30 URLs per week). Note that average crawl rate is ~125 pages per day.
My question is this:
How can I tell that the URLs have successfully been removed? Looking at Google webmaster tools' graph of index status is what I thought was a good indicator, but I am wondering what should actually happen in the results there. Should the blue graph line of total indexed drop back down to a low URL count (as I am expecting), or will the total indexed remain high and the blocked by robots and/or removed URLs increase?
This answer from Google seems to indicate that the total indexed (blue line) should drop. Why then has it not dropped at all after applying the noindex tags and waiting a week?