Fawns, and yearlings add body mass first over antler mass. Small racked yearlings like spikes are generally an indiction of either a late born fawn, or lack of nutrient food sources in your area or a combination of both. Late born fawns are a result of too many doe, and not enough older bucks. When doe are not probably bred in the first rut, a late 2nd rut, and sometimes even a 3rd rut occurs by those unbred doe. So you have fawns being born in mid summer. That results in a late start in life, and a rough road during their first winter.
The whole concept behind antler restrictions is to allow more yearlings to survive, so there will be more 2 1/2 plus bucks around to breed more doe. This in essence if a proper amount of doe are harvested would result in a more well balanced healthy herd.