Oh yeah, it's a very messy system and would be completely terrible if you didn't get the choice to accept the auto-result or fight manually. Based on my experiences, my theory is that the auto-battler doesn't use General abilities. So if you're up against an army with lots of high-DR monsters (that your General's spells would easily kill), then the auto-battler sucks. But if you're facing an enemy army that is tough because of their General's abilities, then the auto-battler makes the fight much easier.
Nah, I don't think it was it at all, since I experienced wild and hardly justifiable variations in results even when no generals were involved.
It got so bizarre at some point that I was even theorizing they accidentally inverted some crucial value somewhere, because it seemed like the harder a battle got, the kinder the auto-solver was to you.
But once again, this is the beta 3 we are talking about. No clue how the current auto-solver is any different, since at least so far I'm absolutely refusing to mod/tweak the default "core" game to any extent.
Party control in Baldur's Gate 3 is a complete mess that begs to be addressed. SAY NO TO THE TOILET CHAIN