Let's talk about Galio.

Even if Galio doesn't hit a 50% + win rate, it doesn't mean that it's fine to have a spell on any champ that have 1.5 AP ratio as well as a 9% max health damage per 100 AP on a 6 seconds CD ability, whatever the winrate, whatever the kit. It is simply way stronger than most ultimate ability and this can't be healthy for the game, in any circumstances.

But I agree once more, doesn't mean necessarily that Galio is OP currently, but he might be tuned in a weird way, leading to a huge disparity between mixed offensive and full offensive, as the last simply gives Galio more burst than any mage in the game (which definitely should not be one of his identities)