Excellent post, BSK!
Great info, seldom even mentioned in the popular (and generally worthless) hunting magazines.
. . . when field-judging buck age, always, always, ALWAYS ignore the antlers.
This particular yearling buck illustrates one of the main reasons I usually don't like antler restrictions being used as criteria in defining "shooter" bucks.
By not focusing on age first, many QDM clubs (and particularly WMA's with antler restrictions) are actually "high grading" their best yearling bucks and above-average 2 1/2-yr-old bucks, mainly leaving the genetically inferior survivors into the older ages classes. Many WMAs and QDM clubs would actually be producing more genetically superior antlered older bucks if they were NOT using any antler restrictions, particularly if they just made yearling bucks illegal (no matter what the antlers on that yearling).
I like to focus on AGE first, while trying to totally ignore antlers.
In the field, a quick focus at the buck's neck is where you start. "Skinny" neck = young buck. "Very fat" neck = 3 1/2 or older buck.
WBy the way, regarding this particular yearling pic above, there are probably no reasonable antler restrictions that would prevent him from being a "legal" buck at the age of 2 1/2. Yet it is bucks like this one that have the most potential to become the very top-end largest antlered bucks whould they survive to 3 1/2 or older.