When we studied tragedy way back in 1967 in Al Biddle's English class, Mr. Biddle set up a hierarchy of sorts, classically speaking:
tragedy: drama dealing with the fall of a noble figure (Remember: classic sense; not Willie Loman and the modern view)
pathos: drama dealing with the tribulations of an ordinary human being
bathos: drama that is overdone to the point of absurdity
Tragedy and pathos were viewed as genuinely moving the emotions, but bathos was articifial because of degree of unreality. Chewing the scenery, I suppose, would be part and parcel of bathos.
