>>149744407 (OP)
When you're learning how to draw, there's a few things you REALLY need to internalize, and a fair chunk of artists never get taught this because they're either self-taught or their teachers didn't pick up the information:
>when you're drawing from life (people, animals, plants, objects, environments, etc), you draw from the outside, then the inside - you draw the outline first, then work your way towards getting the finer details
>when you're drawing from memory, you draw from the inside: you use a skeleton/wire model, or break down your subject into basic shapes
Shelby's 2011 art was technically inferior (in the sense that it wasn't suited for animation), but it is superior to her later 2015 art in that it reflects how she was drawing more from life. Her 2015 art is less stiff and has more depth, but sacrifices any real style while relying too much on memory.