Currently, you gain a number of point's equal to your opponent's ratio multiplied by 10. It's extremely simple.

The previous leaderboard system was practically the same as Graal's default rating system. There was some glitch where players could log on to multiple accounts and reset their rating deviation back to /350, spar a few noobs, then reach the #1 spot pretty effortlessly. It basically rewarded players for avoiding the best sparrers, camping after you reach a number of points, and abusing a glitch. I reported it plenty of times, but staff claimed they couldn't fix it.

iClassic sparrers aren't competitive and mature enough to let a leaderboard like that flesh out naturally. They will always abuse it and turn it into a contest where the most crafty player who avoids the best sparrers and uses the most tricks wins. It's dumb.

The leaderboard many are claiming would be better in this thread is just a flat-out wins leaderboard. Zero measure at all put towards the skill of your opponent. I don't think that they realize that it'd be literally the exact same as the current leaderboard, except without any consideration at all of your opponent's skill. I honestly think people are just bored and looking for something to complain about. In no way is converting a point gain of roughMeasureOfOpponentSkill*10 to a point gain of 1 going to do anything for sparring. No one in this thread seems to be explaining it, just claiming "it's better." I don't understand.
Many who seem to support it seem to be the players with the highest amount of all-time wins. Are you surprised?

The current leaderboard achieves a lot of things that is healthy for the spar community in general, it just drags out for too long. It naturally encourages people to spar boosters/selective sparrers for their points. It doesn't punish players for losing, so people can queue freely and comfortably. It encourages and rewards players for sparring actively. And guess what? There's never been a mess of glitch abusers or alternate accounts ranked near the top.
It should be daily or weekly by default, not seasonally.

But at the end of the day, like I said:
No one has ever used any leaderboard as law of the land to who the best is. After the first few months, it's dismissed as useless due to any number of flaws and we determine who the best is by community consensus. At the very least, this leaderboard's flaws are flaws that encourage people to spar more.