Greg,
The American Fisheries Society chart you use is compiled from data taken over 30 years of length/weights collected by agencies analyzing large public reservoirs. (Most of that data was taken prior to bass fishing crazes that hit in the 70's and beyond)The chart I use is taken from 20 years of pond data.
It seems that "average" pond fish data is different than big lake data.
To keep from being too wordy, the chart I use is more applicable to small water bass growth rates.
If you think about it, bass grown in smaller water bodies grow at different rates, have different population structures, and can change much more rapidly than a 30,000 acre public lake's population of fish.
So, to me, it makes sense to use lengths/weights that apply to smaller lakes and ponds.
That's why I use these lengths/weights.


Teach a man to grow fish...
He can teach to catch fish...