I would say that 99.99% of the bucks out there have no antlers right now or are just starting their new ones. I have heard that if a buck is casterated or looses it ability to produce testrone that strange things will happen with their antlers. One of them is that they will grow continuously, slow but continuious. This is also the reson that I heard that you can find bucks in full velvet at wierd times of the year.
I don't know how true what I heard is but it might be a reason.
Deer will or should lose their Antlers, because of the drop in testoterone that occurrs naturally after the post rut. Once this T-Level hits a certain point , they start to drop them. With castration, which can happen in different forms, should of caused a rapid loss in T. Therefore should of dropped them. If an injury occurrs during the vevet stage, weird things will happen to the antlers. EHD in mule deer tends to not kill the Mule deer, but does effect the testicles and cactus or bucks in velvet occurr. Maybe he was just late in dropping his testosterone, therefore retaining his rack until May. I will keep an eye out for him later in the year, before season starts and see if he his rack is the same or changed.
As a Taxidermist I look at hundreds of Whitetail Bucks every year. I know that I have seen many different ways people judge the size of racks on live deer. I think for the most part they all are pretty close. I'm going to give you some measurements that I have noticed being right on in just about every deer. We have used it in the last couple years and have only been off by about 5-6 inches. We do study the deer while bowhunting so we get a little more time to look at them....