Love the five different area of investigation that you went over, great way to analyze and diagnosis the issue. I would also definitely agree doing a rankings comparison between the two time frames, and not only check what your Google ranking is, but also track the search volume for your keywords to see if it has fluctuated or gone down. Google Trends is a great tool for this as well, as one of your keywords that your ranking for may have just lost popularity online.
For a long time, digital marketers summed up the properties of direct and organic traffic pretty similarly and simply. To most, organic traffic consists of visits from search engines, while direct traffic is made up of visits from people entering your company URL into their browser. This explanation, however, is too simplified and leaves most digital marketers short-handed when it comes to completely understanding and gaining insights from web traffic, especially organic and direct sources.