No one's going to want to hear this, but I'm guessing, as with the mouth, these adjustments were made so that the character performers can endure the Orlando heat and humidity. I wouldn't be shocked if the shoulders are differently shaped to be less arduous on the performers and that the bump in back is to accommodate a cooling pack (or something along those lines). This costume appears to be very consistent with the construction of the Kung Fu Panda Po costume, which is notorious for being hard on performers.