Its a problem of CiCs assigning too few defenders to a target.
How in the world does the size of the squad matter???
Fine, your an 11-15 squad. Wonderfull, you show up with lets say 12 players. I will assign *just your squad* to CAP A34. Ok, then the attackers come in with 10 formations of Ju-88s, and 14 escorts. You are outnumbered 2-1 in players and almost 4-1 in a/c. Did that help? no it did not. Why? because squad size does not matter, what matters is ***how the CiCs divvy up their forces***.
If you are a 4-6 squad and are assigned with one other 4-6 squad to CAP a base, tell the CiC that that is not enough. You should be paired with at least another 7-10 squad minimum, and preferably a larger squad than that.
Squad sizes in and of themselves has NOTHING to do with it.
That being said, I know the problems that you are speaking of, and I am sympathetic, I have been there myself, but you are aiming at the wrong solution my friend.