Amumu isn’t exactly a world-beater at the high end of League’s ranked ladder. For a long time now, he’s barely scraped by in higher-skilled play while also bordering on overpowered for the average player. So what can be done about that?
As a champion with a long history, it is not simply enough to rework a champion, for it must be done correctly, with Volibear being one good example, However, that takes time, and with a growing number of champions falling out of touch with the times, Riot have started to look into "reshaping" them.
For those who aren’t familiar, the core of the change is that Amumu can store two charges of Bandage Toss and his early game is buffed. That new power came with tradeoffs in other parts of his kit, of course.
The reason for this, developers say, is that they wish for champions to hold onto what makes their identity, but also to make them viable in both higher and lower levels of play.
The goal is to enhance what current players of the champion love about their champ or at least retain it as best possible. However, that player base isn’t homogenous. They often want different things, and it’s a careful dance to respect as many of them as possible while also making the changes that will best serve everyone.
On that note, all manner of testing was done, to make sure it was done right the first time, as reshaping champions is only short, timewise, when compared to reworking them. So, to be able to reshape the entire roster, the first time must be the charm.
Aside from that, Riot can't expect players to keep relearning their main over and over again, so the changes will be a one-time thing, until further notice.
We can expect more champions to receive this treatment, and make their kit keep up with the recently released ones.