The way we determine wether or not to hot fix comes down to our estimated win rate growth and where we expect them to be for players with zero experience in the champ. In Gwen’s case, we estimated that she’d grow a little under 10 percent given her fragility and high mechanical burden. Her win rate on launch plus our estimate still put her under 50%, so we did a cautious buff in order to try and get her more in line.
Yuumi was actually a learning experience for us, that we should be factoring larger growth estimates for weirder champs. That’s why these buffs are so minor. We could buff her to be 50% right now, but the goal is to buff her to be long term balanced. Like everything we do, the live environment is much different from our testing one, so we monitor the champ closely as the players grow to learn the new one.