In almost every LoL meta, there is often one side that is more interesting than the other . In most of them, the blue side dominates slightly , as it picks the strongest champion available. The meta is considered interesting, when the meta's dominant champions can be countered, allowing the redside to be viable from a counter picking perspective . The game is considered balanced if the Blue Side is between 50 and 51% of winrate (if it is dominant, if it is at 49% it is also balanced). There were a few metas, where the redside was favored but it wasn't necessarily the most interesting . In these Worlds, the blue side ended up with 52.5% winrate, which is enough to make it OP according to Riot's criteria. Games.
Why is he OP today?
If the blue side was so strong during these Worlds , it's largely because of Yuumi . The little cat has finally succeeded in also rotting the competition, thanks to its attachment mechanics, which makes it difficult to counter . You don't necessarily need to have a winning duolane for it to shine, since the counter pick can be taken on a sololane or even better, in the jungle . Yuumi will therefore leave her ADC, to go roam with the jungler , whether to take an objective or support another lane. Since she's untargetable, she doesn't take AoE damage, allowing her to attach herself to a new ally if the first one dies. Then his heal generally allows his team to take the advantage if the fight lasts too long , especially in early/mid when the burst is not powerful enough for OS a champion. Yuumi's ultimate, which is also a formidable tool in teamfights, is ultimately just the icing on the cake. And when you know the power of her R, the fact that it is just the icing on the cake makes the champion even scarier.
Yuumi is therefore a safe first pick , who cannot be punished. This forces the redside team to ban her . This therefore means that they literally play with one ban less during the draft phase. It is now necessary to add the second champion of these worlds who posed a problem: Caitlyn . The sheriff was a very good safe pick bot , providing a good lane phase while still being flexible enough not to be fully countered (even if she wasn't dominating, she wasn't supposed to lag resources). The Lucian / Nami duo took their place a little at the end of the tournament, which balanced things a little more , also forcing the blue side to think about this ban. Nevertheless, the redside ended up playing on average with a ban and a half less (two during the Yuumi/Cait period, then a rebalancing with only the Yuumi ban when the Worlds ended with the Lucian/Nami domination).
Was he that strong?
If we base ourselves only on the BO5 where each of the teams won at least one round , we arrive at a result of 11 blue side wins against 12 red side . Seeing this, one might think that the redside is n't that much of a disadvantage , but that has to be balanced against another statistic: no losing team chose to stay redside , or take it back, even if they had already won a map on this side in the soundtrack. Here the statistics are both misleading, and at the same time revealing. The teams that won a BO5 of the Worlds were the teams that played the best on the redside , but the latter was not the best side despite its superior winrate. It is also very likely that all the teams trained more to play redside than blueside, because they knew that if they took the advantage, then they would have to play on this side , which allowed the redside to have a better winrate, despite being the weak side.