Incorrect Techniques Reduce Pagerank Value.
Every site gains its own pagerank value over time. When it improves this in a positive direction, the pagerank value can rise. On the other hand, due to incorrect techniques, there is also a situation where the pagerank value decreases to 0. In this case, the site has a negative pagerank value. That is, it has been penalized. Even if it is removed from the penalty by fulfilling positive conditions after a while, its having a negative pagerank value is kept in the search engine lists.
Returning to the Old Ranking Takes Time.
Therefore, even if sites whose pagerank value has fallen to negative and entered the blacklist fulfill the conditions and get out of the sandbox filter, the site cannot return to its old ranking, and even if it does, it takes a considerable amount of time. The biggest reason for negative pagerank is that the pages consist of artificial followers and unnatural hits.
