As a lot of you have noticed, the front page algorithm changed. It's been almost identical for a decade, but on May 10th we decided to change it.

The FP formula
The old formula caused fp to constantly be stale. It rated saves with a formula "votes / time", so the more votes you got in a short amount of time, the higher it ranked you. Once a save got FP, it would get even more votes, causing it to stick. Being on FP was such a visibility boost that it would create a feedback loop where your save got more votes due to being on FP, thus got a higher rank by the formula. Eventually the votes slowed down, and many saves dropped off, but it was also very common for saves to stick the entire week.

The new formula tries to solve this by using weighted randomness to pull a different list of saves each time. Rather than showing only the top ranked saves for the week, it looks at all potential candidates, weights them based on their rank, and pulls a sample from that list. Higher ranked saves are more likely, but not guaranteed to appear. Lower ranked saves are unlikely to appear. But given there's 15 slots, some of them will show up, giving them a chance. With the higher rate of churn, more saves get viewed by more players, and the FP-deserving saves get upvotes.

This is why FP has appeared more "random" the past two weeks. A qualified save will appear and disappear many times throughout the week. "Getting FP" is now less of a distinction, instead more saves from more users will take up the FP slots.

Effects / Future
So far it seems to be working. The amount of votes placed per week is the same (< 2% variance) but is distributed across more saves than before. "Engagement", which I'm going to define as the number of views per week, is up. But my metrics on that are so bad it's actually meaningless and might be influenced by bots. I was worried FP quality would tank, and initially I saw some dubious saves but that sorted itself out quickly.

In the next version, we plan to add even more ways to find recent / top saves, including a way to view the top saves of the week if you'd still like a view like that. You can see a preview in the snapshots.

Thanks to @savask for spearheading this whole effort. Without him none of these changes would have happened. @Simon did the actual website changes. All I did was write a forum post. Thoughts / feedback welcome below.