/dev: MMR-to-Rank Distribution

Hey everyone. In today’s Dev Update, we talked a bit about some changes that we made to Ranked MMR distribution and the impact it has had on your climbs so far this year.

In this blog we want to dive a little deeper into our goals overall for Ranked, the rationale for these changes, and some of the things we want to do in the future to keep League competitive, fair, and fun for everyone across all ranks.

Fair Competition for Everyone

In order to be a healthy and competitive game, League has to be fair. We’re continuing to ban cheaters, investing in better detections for inters and griefers, building better systems to move alt accounts out of lower-skill games faster, and combating Ranked abuse done by smurfs. The next area we’re focusing on is ensuring that you’re in games with roughly evenly matched players with reasonable queue times.

When we first launched the Ranked system in 2010, players were generally much more equal in skill. And the difference between someone at the bottom and the top of the ladder wasn’t that much different—unlike today.

As time has gone on, you’ve all gotten much better at League and the top players have improved at an even faster rate. And while we’ve made a handful of changes in the past (like adding Iron, Grandmaster, and Emerald), it’s been a while since we’ve taken a hard look at how MMR is distributed across ranks.

So, we felt it was time to do that.

Adjusting the Distribution

At the core, we want players of all ranks to have a similar spread of demonstrated skills and understanding across them—this means that players in Gold IV through Gold I should have a baseline understanding that when a jungler is seen top-side, they should push lane to get priority to take dragon, for example.

And when we took a look at whether or not we were still achieving this goal, it was clear that there were a few locations where that wasn’t the case, primarily at the bottom and the top of the ladder. Additionally at the bottom of the ladder we want to give players still learning champions and the Rift the ability to play against players in a similar part of their journey. And this is what we think Iron should be for.

Historically, we’ve had an outsized population of players in Iron—around 14% of players globally, mostly consisting of players who’ve been here (or bouncing back-and-forth between Bronze) for years.

These players who’ve been Iron have a moderate, and sometimes deep, understanding of champion and gameplay mechanics. They just may not apply it consistently to their gameplay. And someone who understands how to play Viego and how to use his passive effectively is not the same as someone who doesn’t know what a Teemo is.

So we chose to adjust the MMR-to-Rank correlation to get the more experienced players out of Iron and into Bronze, so Iron can truly be a home for players who are still learning the ropes (and finding their love or hate for Teemo).

We’ve seen a lot of success in this change so far, but we do think that it still may not be enough to really distinguish between these skill levels, and there may be a need for an entirely new rank below Iron in the future.

At the other end of the spectrum, we’ve had perhaps a more drastic difference between demonstrated skill across players at the same rank: Diamond.

Last year (but really, this has been true for the last several years), the difference between a Diamond IV and Diamond I player was roughly the same as a player in Bronze IV and high Silver. This made the experience of climbing through Diamond incredibly painful, and, in order to align with our goal for Ranked, we needed to make a change.

So, similar to what we did at the lower end of the ladder, we decided to re-assign the MMR-to-Rank distribution to put players at the higher end of Diamond into Master. These players were likely historically already playing in games with Master players, and maybe were Master at some point.

Similar to Iron, we’re keeping an eye on this and think that a potential follow-up is that we may also need a bit of expansion at Apex tiers, given that there’s now more of a difference between a 0 LP Master player and a 900 LP Master player.

As a result of the widening of the MMR range for Master, though, it has made the LP requirements for Grandmaster and Challenger higher, even though there’s the same number of players there. We’re considering what changes to make here for next Season and, as always, will let you know what we’re thinking as we get closer.

The Future of Ranked

We see changes to all systems—including Ranked—as a natural part of League being a long-lived game. And we have a lot of work planned on this system as a whole.

Right now some areas that we’re focused on are improving autofill and secondary role parity. As of writing this, we’re planning to roll this out to EUW in 26.4, with OCE and VN to follow. And if all of these tests go well, we’ll roll the changes out more broadly as 26.5 goes live.

We’ll also continue to keep an eye on Apex tier duoing, and are generally quite happy with the adjustments that we made in 26.4 to balance queue time and match quality.

We’re also working on a plan to resolve LP gains in Master+ games. We’ve seen a lot of instances of +10/-30 LP for players at this tier, and we’re hopeful that we’ll have a fix for this soon.

And, finally, we’re still evaluating ways to make Mastery better representative of performance, especially in shorter games and for the range of roles. This should help make the LP gains and loss protection from Aegis of Valor more consistent for everyone.