If you think about this logically you can see that there is an area where the current ENY/Balancing system has a potential weakness.
First, I am starting with a few logical assumptions.
1.) The current ENY/Balance system is intended to hinder the numerically superior side from just numerically overwhelming each base capture.
2.) The current ENY/Balance system applies the same percentage calculation to the player population all the time (from a minimum of 70 players to a maximum of 600 players).
3.) With the current base capture system, the work (i.e. what you need to do in order to capture a base) is static.
Since the work required to capture a base is static, the chosen percentage calculation must work over a wide range of player population. It is my
personal belief that an attacking force of more than 15 players constitutes an overwhelming force that is detrimental to game play. I'm sure this number can be argued and if there is sufficient defense then the number could even be significantly higher, but 15 vs. 3 or 4 defenders is an overwhelming attack in most cases.
If you look at the images the OP provided, you can see that with the current system as the total number of players in the arena goes up, the potential for numerically unbalanced attacks also increases. And that is a genuine weakness of the current ENY/Balance system.
There are a few different options for addressing this issue, but I want to get the core of the problem discussed first.
Baumer