It's reaaaaaaaaaaally difficult to draw any significant conclusions about the Fred update and why people were hit.
I think it's best to sit tight for a while. For two reasons...
Firstly, this algo change is likely to be further optimized in the coming weeks. Some sites that were unaffected might start going down (or up), and sites that were affected might see an improvement (or a further hammering).
Secondly, the reason we can't really draw any solid conclusions yet is because of lack of data.
Looking at a handful of reports about people's websites on forums or small blogs is fairly pointless. Even if you had 1000 affected sites to analyze, it would still be very difficult to draw conclusions... and any conclusions you did draw are likely to be invalid due to a small sample size of data.
We need to wait for those who do have data to analyze and report their findings. Places like Moz, Ahrefs, etc.
They crawl billions of pages every day, and are in the best position to draw meaningful conclusions about the most likely causes.
Also, keep an eye on large SEO agencies. They also have access to a lot of data through their clients - and, also, these agencies will be under a lot of pressure to help their clients sites recover.
They will test recovery solutions, and will eventually report what works.
I think everyone needs to not be hasty... relax. Whitehat SEO is a long term game.
Even if you took a hit, there's likely things you can do in the future to recover. Just don't be hasty.. you might end up making changes based on invalid conclusions, that in reality will actually have 0 affect in helping you recover...
You might even hurt yourself further.
Sit tight.
Then when you're armed with more meaningful ideas from those with enough data to present them, you can consider the best moves to recovery.
