Alright, so, as a storyboard artist myself, I'd like to point out that storyboarding here can actually work - We've seen this all the time in more professional works with 3D animation.
The problem here is that I don't think they even storyboard. And I say this because listening to the commentary tracks, they talk about how they cheat by putting the characters near walls.
See, storyboarding, especially with fights with large groups like this take a lot of time and careful planning, obviously because you want to be able to track each character's movements and maintaining the continuity of the scenes. Normally, to do a complex fight like this, you'd want to go with at least two different storyboard methods - The above shot overview and of course the action shots.
The above shot overview has you tracking each character with markers on a very basic representation of the area - making sure to mark all significant locations on the map (stuff like stairs, statues, debris... All that jazz) and have them be integral to work with your fight choreography. If I had to make a similarity to a real life action shot, imagine some of the fight scenes that Jackie Chan had in career:
https://youtube.com/watch?v=B215g-Evv0U While I'm not going to claim the full process behind the fights like this, there are several movies that do have to take into account the location in which action scenes take place in, and will have to plan accordingly - Because yes, storyboarding can be used for live action scenes as well.
One thing you'll notice in a lot of the newer fights in RWBY when compared to the older fights, is a severe decline of using the environment in the fight itself. If anything, the fights in RWBY now-a-days are like they take place in the arenas you'd see in 2-D fighters. I.E. not having any real impact on the environment that actually affects the fight in any meaningful way, at best, you'll have a character now-a-days using dust to summon a pillar of ice or earth or climbing a wall.
In contrast to the Jackie Chan clip, notice how during the fights there's a use of the environment he's in - Whether it's chucking a bad guy in between the small gap of escalators, using the clothing racks to defend or trip his opponents up, or even using the stairs to do the same thing - There's an excellent use of the background here to make the fight all the more fantastic.
And the thing is... This sort of thing would be EASIER with 3-d animation, at least from what my colleagues who do 3d animation have told me (they could just be fucking with me, so *shrugs*). Why? Because Jackie Chan is a perfectionist, it takes hours to get the shots just right due to the fact that humans make mistakes, and that a lot of the other actors and martial artists can't usually keep up with him at first. But with 3-d animation, you'd have complete control of the characters in that regard.
Back to my point about storyboarding, and the lack of it in Rwby, you can easily tell that they forgo at the very least, the above shot overview, due to how messed up the continuity and how the characters suddenly transported into the universe of Dragonball Z and can now use instant transmission. At least my my perspective, they don't storyboard at all - Or if they do, they must REALLY suck at it.
