A couple of days before the new year we sent live our new theme design on our Shopify store that we, which has a lot of different features to our last one, the main one being that we have a new product filter by tags sidebar that when used creates new URL paths. A week after the site launched we noticed in webmaster tools that more pages were being indexed and also our rankings and traffic had improved slightly. Last week we had a huge drop in rankings for our site and I mean massive so although we can't rule out an algorithm change or penalty it does seem like another issue because nothing has changed in terms of our SEO work or content except for the site structure itself. We have just noticed that 2 weeks after our new theme launched, along with the growing number of pages being indexed in our webmaster tools there was now around double the number of indexed pages being blocked by our robots.txt where as before the new site we had 80 blocked and 2000 indexed, we now have 6500 indexed and 12500 blocked (and growing). Does anyone know any reasons this could happen?(other than that because the robots file blocks "+") And could these be a reason for such sudden drops in rankings and traffic? I wanted to stay away from the talk of a possible google update because the changes seem so drastic in rankings and indexing of our site, with both of the big changes seeming to line up by date and as more URLs are blocked by robots we are seeing a drop in rankings in correlation with it. Any ideas?