My guess would be that the button buck came through the winter in better shape than the 8 point simply because the 8 point most likely had no reserves left (because of the rut) by the time winter hit. Now come spring the button buck is in good shape, ready to go, and the 8 is still recovering. While he is recovering I would guess the body naturally puts its energy into building the body back before the antlers. I would also guess that at some point that eight catches up to and passes that button buck in growth rate as eats the new growth, replenishes his mineralsand his health improves.