It's very clear that the size of a bucks antlers at 1.5 mean nothing when predicting his antlers at maturity. The only way we could high grade the gene pool is to not shoot bucks till they reach 4 1/2 and then take the best ones out. High grading before that age is a myth.
You simply do not understand the meaning of high grading. As I explained before it has nothing to do with a change in the gene pool, It is simply the effect of harvesting,on average, the best buck from each age class and leaving lesser quality buck advance to the next age class. It has nothing to do with those bucks doing the breeding and degrading the gene pool.
While it is true that no one can tell the potential of a 1.5 buck, Dr. Kroll's research shows that a 1.5 spike takes 3 years to catch up with a 1.5 6 pt. So while we don't know the potential of the spike we do know that the 6 pt. has more potential to develop a large rack quicker than the spike. But, because the 6 pt. is harvested as a 1.5 it never comes close to reaching its potential and the spike may be legal as a 2.5 and not live long enough to demonstrate that it had the potential to become an 8 pt. This results in smaller average rack sizes for 2.5 buck due to ARs.