Most of the time you will rotate and then use translation to add extra umph when needed. But It depends on the design of the rig and the character design.
Melvin doesn’t have a chin, so he should be mostly translated, and I can’t remember off the top of my head but I think Baker has a Jaw control that you translate but that will actually rotate the jaw deformation bone. (the deformation and control bones are separate and you can’t actually translate that def bone.)
Hope that makes sense.
