Unfortunately - and unsurprisingly, considering this is Creative Assembly - there's currently a major bug introduced in the new patch. They updated the calculations for splash attack damage, trying to make it more uniform and easily understandable as a stat.
However, they fucked up big time and managed to inadvertently nerf the hell out of a lot of units with low model counts that rely on splash damage for their combat performance - most notably monstrous infantry and monstrous cavalry. Which is to say, pretty much the entire Ogre Kingdoms roster.
It's a double shame because the actual content of the new Omens of Destruction DLC is really, really good. What little I fooled around with the Golgfag Maneater campaign last night was insanely fun from a grand strategy perspective; Golgfag's mercenary contract mechanic is very well done and captures the feeling of a world-spanning sell-sword perfectly. Really sucks to see his new, top-tier anti-infantry Maneaters unit struggle to win a 1-vs-1 against a unit of regular Empire Spearmen, though.
CA have seen the glitch and are promising a hotfix will come out early next week. There are also mods on the Steam Workshop that revert/patch the splash damage back to the values from the previous release. In the meantime, I'm going to try out the new Free-LC lord, Arbaal the Undefeated. I've heard very positive things about his campaign, and he seems to be mostly focused on mortal infantry, so the bug shouldn't impact him too much.
