Again, this is about the performance of an individual pellet rather than the whole load. It was originally just intended to give some perspective to the energy in each pellet of a 00 load.An individual pellet isnt that great, but 9 or on something like #1 or #4 Buck, 15 or 27 pellets that will penetrate plenty deep.
As for #1 or #4 buck, the total energy of the load will be divided equally over the number of pellets. So if the #1 or #4 load has the same energy as a 00 load, and there are 15 pellets, each pellet only has one fifteenth (or one twenty seventh) of the total energy. Penetration will be affected by both pellet energy and pellet diameter. Hence since the #1 and #4 pellets are smaller, it takes less energy to drive them into a substance. But they have less energy per pellet so it may be a wash.