They dynamics of the primaries are totally different now, so I'm not sure historical analogies are super important.
Everything is front-loaded now. And there's less time to take advantage of surges and money raising, that traditionally comes on the heels of an early primary victory.
That said, victory begets victory. Perception is important. If Obama looks like a winner, and Hillary looks like a loser, its likely to become a self fulfilling prophesy.