So around the end of September I lost around 75% of my organic traffic. This is just after a Google Update. So I immediately disavowed any potentially toxic backlink I could find but there was no bounce back.
Then I was at a SEO conference in London last week and I got talking to a guy to did SEO for one of the biggest sites in England (Top 10). He said that he also took a dip around that time and it was due to his sites poor Dynamic Architecture. Once he fixed that, his sites rankings started to revert back to their previous positions.
Not 100% sure what that means in terms of my site or how it would affect rankings so drastically.