Riot's game design manager David Capurro has laid out plans for a more systematic approach to balancing League of Legends' champions that puts more emphasis on the average player.
Previously, Riot's general approach has been to "balance for Plat+ play", Capurro said in a blog post, but now the team will balance for four distinct categories of players, each with their own defined criteria for what it means to be overpowered. "While some may argue that the game should be balanced around only the very best players of the game, we think a balanced experience is an important part of what makes League compelling regardless of skill level," he said.
I'll go into detail about what overpowered means for each of the four groups below, but the key takeaway is that a champion will be considered overpowered if they're overpowered for any of the groups. They'll only be considered underpowered if they're underpowered for all of the groups. Riot's priority is, first, to balance overpowered champions, then balance universally underpowered champions, and then drill down into the outliers.
"Average Play" is the first group, which contains everyone below the top 10% of solo queue players. Win rate and ban rate will be the two deciding factors here: if a champion is banned less frequently than the global average of around 7%, they will be considered overpowered if they win more than 54.5% of the time. The more often they're banned, the lower that win rate threshold will drop: reduces as ban rate increases, and if a character is banned at five times the average rate then they'll only have to win 52.5% of their matches to be considered overpowered. Conversely, characters are underpowered for this group if they win 49% of matches or less.
"Skilled Play" is the next group, which is the top 10% of solo queue players. They're treated the same as the first group, except that the threshold for being overpowered drops—below the global average ban rate, a champion will only have to win 54% of matches, rather than 54.5%, to be considered overpowered.
The third group, "Elite Play", comprises the top 0.1% of solo queue players. For this group, win rate isn't counted because of the small sample size—the number of players is "extremely limited". However, because these players know the game so well Riot can simply use pick rates and ban rates to analyze how powerful champions are. At this tier, champions are considered overpowered if their ban rate is 45% or more, and underpowered if the combined pick rate and ban rate is less than 5% (if the champion isn't even on players' radars, basically).
The last group is pro players. Because of their skill, Riot will again consider pick and ban rates: champions will be overpowered if their combined pick and ban rate is 90% or more in the current patch, or 80% or more in consecutive patches. Like in Elite Play, they'll be underpowered if their combined rate is 5% or less.
Remember, the framework is just to decide which champions need balancing, and doesn't address how they will be balanced. "Our hope is that the above system for identifying imbalances allows us to more easily move beyond what is out of whack and get into the why that’s the case, as well as how we ought to address it, Capurro said. "Put simply, the framework more easily gets us to the point of agreement on the fact that a champion like Hecarim (for a recent example) is overpowered, and then we get to work on how to fix it."
The full post is worth a read if this stuff interests you: Capurro talks about why high play rate isn't a factor in balancing, how Riot will deal with high mastery curve champions, and how it will account for regional differences.