I believe it is the 20 most valuable finishes within the last 18-24 months. They start depreciating value as they age, as well.

True. But that formula us also changing.

Due to the rampant WPPR farm abuse that devalued WPPRs by making it an attendance contest rather than one of actual skill (If you just showed up to enough farms, you'd find yourself in the top 300 without even trying) more emphasis is going to be placed on your efficiency rating going forward. I don't exactly understand how that works, but basically, your performance in ALL tournaments will affect your rating, not just the ones that show on your card. This will cause some people to fall hundreds of spots. Some will go up as well. It's retroactive to 2021 I believe so there will be an immediate shakeup when it goes into affect (next year I think?)

There's a very long and boring thread on this at tiltforums if you want to try to understand how it all works. I personally do not. None of this will change the amount of tournaments I go to - I've always preferred doing a dozen or so larger events a year than just going for brutal quantity. Farming isn't really that much fun for me.

Some people are upset about the changes to the formula (mostly lower ranked people who are going to drop from 400-700 (like who gives a fuck)), some people like it, some people don't care.

I definitely think something had to be done. You had the top 200 absolutely STOCKED with people who basically only attend one venue that has tons of high value events because they are "lucky" to live nearby and it was really distorting the ranking system.

http://tiltforums.com/t/wppr-v6-0-sneak-peek/8325

It’s the twenty events in the last 3 years that give you the most points. After a year an event is devalued, after another year it’s devalued again.

Ex. Today you win an event worth 10 WPPRs. Next year that event is worth 7.5. Two years from now it’s worth 5. Three years from now it’s worth zero.
You take the twenty events that are worth the most, add them together and use that total to rank you among all the players.

Starting next year it will be your top 15 events and if you’re in the top 1000 your efficiency will be factored in as well.

I just wanted to reiterate this point re the upcoming change to include your Efficiency % as part of the ranking formula. As noted above this will ONLY affect the Top 1000 in the Open standings, so for the vast majority of people it will not play a part at all.