I can only speculate. For faces, I'm sure there's tons of manual work to be done to reduce the uncanny valley, especially when it's being mapped onto a differen

I can only speculate. For faces, I'm sure there's tons of manual work to be done to reduce the uncanny valley, especially when it's being mapped onto a different facial geometry (like King Kong). For body movements, perhaps the collisions and interactions with the virtual world require a lot of manual tweaking to get them looking realistic.