That isn't apparent to me, because I expect that Huckabee's drop is due to all the dirt on him coming out, not necessarilly folks taking a more favorable view of Mitt than they ever had.
Agreed that the truth about the Huckster is what's sinking his ship, but Mitt's had a lot of stuff to deal with as well, and has kept his base. Unfortunately, that's more than I can say for Fred, I'm waiting to see his resurgence.