UPDATE 2/28: RiotScruffy took to Twitter to correct a statistic featured in the most recent developer update after a mistake was pointed out on the League of Legends subreddit. The previous statistics included games of ARAM and URF, which the community viewed as misleading since competitive balance revolves around and matters most to the standard game mode on Summoner's Rift. 

RiotScruffy provided updated statistics and said that Riot Games will be putting out another developer update on Friday,  March 5 that will, among other things, include the correct statistics updated with a new week of data. 

Original story: 

Riot Games released a developer update sharing thoughts on the item changes implemented for the 2021 League of Legends season. The thoughts are primarily about whether the creation of Mythic Items, which was the centerpiece of the pre-season changes, has carried out the game diversity the items were originally designed to accomplish. 

Mythic Items were introduced in pre-season as a class above legendary items that champions could buy one of to augment the rest of their item builds while simultaneously having an option for a significant first item spike. 

Lead Gameplay Designer Mark "RiotScruffy" Yetter outlined how the Mythic Items' success was perceived internally and how that success is measured by Riot Games: 

For mythic items, our goal is that “no champion chooses the same mythic in 75%+ of games.” The percent is a bit arbitrary, but we feel it represents a champion having viable options to think about each game....In patch 11.3, 88% of champions hit the goal, which we're very excited about. This is a dramatic increase from historical levels: In 10.22 (the patch before preseason), only ~20% of champions would have been successful."

The rest of the update goes in depth on each champion class and its respective members' percentages in building applicable Mythic Items. Tanks are the only class with no hard-binding, showing unparalleled Mythic Item diversity, whereas mages are considered the biggest flop currently in terms of mythic items. This is due not just to the clearly defined and familiar strengths of both Luden's Tempest and Liandry's Anguish, but the sheer irrelevance of Everfrost.

Fortunately, Riot Games has nudged Everfrost up to be a viable alternative to the other Mythic Items built from Lost Chapter in Patch 11.4, and the Legendary Item class is also receiving adjustments based on build rates either being extremely high (Zhonya's Hourglass) or extremely low (Silvermere Dawn).