To add some clarity here, the balance framework takes into account winrate, pickrate, and banrate when flagging champions for nerfs.
In short, this means that just because a champion has >52.5% winrate, does not mean it is strictly overpowered by our standards.
That's not to say some current chamions are not 'OP' atm, but that I would be careful only using winrate as an indicator for what's imbalanced.
Our framework is also our system to point out distinct outliers. When we look at each patch, we also investigate champions that are close to our metrics, and evaluate if there's something that needs to be addressed.
As stated elsewhere in the thread, with our preseason changes, some of these champions may be beneficiaries of outlier items. If we think the class/item is an outlier, we may choose to hit the item instead of directly hitting the champion. The same works in reverse for potential buffs in preseason.