Just remember the numbers presented are just averages for an entire population. Individual bucks will display individual growth rates. Just because a particular bucks displays rapid antler growth rate when young does not mean he will continue that rapid growth rate for the rest of his life.
I don't think this chart is useful when reviewing the potential of an individual buck. But I do believe this chart is useful--and relatively accurate--for assessing average scores per age-class for a given property. I plugged in the numbers I have for average gross score per age-class in my area and the calculations proved amazing accurate at predicting average score for other age-classes.
For example, if the average gross score of 2 1/2s is 60% of maximum, and 3 1/2 is 78% of maximum, and 4 1/2 is 92% of maximum, you can use the average gross score of 2 1/2s in your area to calculate what the average gross score of 3 1/2 and 4 1/2s in your area will be. But remember, when calculating the average gross score of 2 1/2s, you must use ALL 2 1/2s, large and small. Not just the ones hunters have killed, because hunters high-grade bucks for the largest antlers.