Ok so i have been trying to figure this out for about a month now.
The case: I have a blog network with unique content on each post and at the end of each post each blog links to x1.com/unique-url-for-each-post before linking to x1 in the post i use a redirect with like this: theblog.com -> redirect-url.com/redirect.php?=x1.com/unique-url-for-each-post -> x1.com/unique-url-for-each-post
(all links at the bottom of the posts have no-follow)
For some strange reason about a month ago all blogs which i have done this on lost around 90% of their traffic.
Could this be the cause of the penalty? Is this type of linking considered as link farms by google?
All help and tips are greatly appreciated!