I noted a number of their issues here:
This being one of the things I mentioned:
They don’t get reduced damage in hordes or around other enemies. So it’s like getting a Chaos horde of marauders, but even marauders don’t hit quite as hard. They’re a pinch less than gors.
The problem with “ambushes” is that the beastmen are basically magicians. They spawn right on you or right next to you because you “aren’t looking at them”. It’s silly. There won’t even be a “climb in point” like a hole in a wall/ground or something like Skaven have. They just “poof” in because you weren’t looking at that spot at that exact moment. There also shouldn’t be 50 beastmen on top of you that can’t even have the decency to breath before they hit you. Any audio would be great. They have like the most soundproof, softest hooves known in their world or ours.