I read somewhere that seo smartlinks is not good once your site starts getting bigger because the internal links will be very dynamic and keep changing as you add more posts. They mentioned that sometimes google will interpret internal links being changed as link manipulation. (When the internal links keep changing but the information around the link is not updated)
I'm not sure how true this is, but I'm no longer using seo smart links on any of my newer sites. And yes, all my sites using seo smart links have plummeted when they hits around 100-150 pages. It might just be coincidence though, I'm not sure.
I used to love google dance because I knew it meant my site was going to come back stronger, but now whenever a site drops, I get very worried and question if I did anything wrong. I have many sites that have dropped and never come back even with consistent building for over a year (I've finally found the courage to stop working on those so I can focus on new projects).
A lesson I learned is sometimes whitehat isn't good enough. Your site can be 100% whitehat, but if it doesn't give the users what they want, there's a chance you will drop off the radar eventually or once google has collected enough metrics on your site. (High bounce rate / users clicking block because their annoyed they didnt find what they were looking for etc.)
My old sites had average time on site 4 minutes + fairly clean/consistent link profile (they all still got penalized by google). My new sites have average time on site 10-15 min but their still quite new and their ranking is very consistent.
What is your current bounce rate/time on site? 100% unique content usually doesn't mean as much anymore from what I've seen, it has to be 100% unique and high quality for long term ranking. 100% unique seems to get rankings short term but drop off after google gets a bit of stats on the user interaction with it. Of course it depends on the niche and the competition from what I've noticed...
I would recommend finding the pages with the highest bounce/lowest time on site and either fixing the content to answer the users query, or noindex/******** those pages.