{SOLVED} Blender rigs only working well with POSES?

So, I'm making some height difference animations using redhead's height sliders and custom rigs, and I'm noticing that despite everything looking beautiful in blender, they look absolutely horrid in game. Now I know it's not conflicting with any other sliders/presets because I have been testing this on a completely vanilla game the entire time, but I can't seem to figure out what is wrong, and I've been trying to figure that out for nearly 24 hours!

EDIT: Deleted additional information because I don't care to find out anymore. So I'm marking this as solved, since I can't delete the thread entirely.