I have noticed a very strange and obvious issue in the past few weeks. When a novel goes premium, its ranking suddenly improves. There were some obscure novels (like Gourmet or Pet King) that had a very tremendous change after going premium. This was easy to trace before the viewing of past weeks of ranking got limited.
What is more obvious is the new novels in the pool. When they get released, they will gain a boost of more than 20-40K votes, jumping sometimes to top 10, then suddenly, the following week they will only have 1-2k votes.