TL;DR - Yasuo was 58% day 1 because of beautiful Yas mains like yourselves dedicated to the way of the wanderer; as the patch went on we had FoTM players try to get freelo on one of the hardest champions in the game and they brought him back down to ~55%.

• I run the day 1 winrate reports at Riot (aggregation of all plat ranked games across the world the first day the patch drops). I was a little flummoxed by Yasuo rising to 58% in NA Toplane (my data set had around that number too) just as everyone else was. Then there was the bug, and sure tank Yasuo was also helping him climb for the last month or so...

• ...But the real bamboozler was that he then dropped and settled in this patch around ~54-55%. While I get some variation between day 1 winrates and the settled patch winrates, it rarely happens with high playrate champions like Yasuo (especially to the extent of ~3%).

• My best explanation (which I thought you guys would appreciate) is that because Yasuo has one of the most extended mastery curves (basically it takes A LOT OF GAMES on Yasuo to cross even the ~50% winrate threshold relative to other champions), we had a flood of non-Yasuo-mains (** cough ** the Riven buffs weren't enough so they went and played Yas ** cough **) that brought his winrate down from day 1. Also I like the saying that "everyone is a Yasuo main, some just don't know it yet", so I'm gonna guess that when some people saw him at the top of the winrates for ranked they thought "now I will become the hero of this anime!"

I double-checked his playrate in ranked for this patch and it went up despite his banrate also spiking so I think this explanation is close. Idk, there might be some other factors that caused him to settle, but I like the romantic idea that for one day the purest ranked Yasuo mains tore up the ladder with a 58% monstrosity because they got secret bug buffs.