Well hes purdy, the thick neck tells me hes older then 3. If he was up at the end of his life he will still grow a decent rack but because the body requires more the nutrients and minerals for the rack start to be utilized elsewhere leading to a rack that will eventually start to decline in mass and size.
My rule of thumb if you can track deer for several years;
year 1-3 growth in body and rack
years 4-6 will start to peak at max capability
years 7 on up rack may remain for another year but will start to decline at this point hes pretty much a senior citizen.