Beane and McDermott know our defense has multiple holes with all the injuries.
Getting a back like Henry could allow for a change to a ball control offense thats goal is to keep the defense off the field as much as possible. In a sense, you'd be fixing the defense with one move on offense rather than multiple moves on defense. Think about it, what's easier? Trade for an absolute beast of a RB or a starting CB, LBer, and DT?