There could be a lot of reasons why these maps are failing. I know on some of them, when we are pushed into our assholes and trying to find a way to flank or break through the enemy line, there are times when the out of bounds prevents us from using an avenue of approach.
Sometimes there is not enough weapons for support, or weapons are too difficult to employ for their purposes (the clumbsy feel of automatic rifles is a good example).
Sometimes there are flags where static objects are placed in such arrangements, and flag zones are so small, that players are forced to run through bottle necks which are easily defended, and capture flags which any skilled mortar man can quickly clear with a single round.
There is a lack of control on most FH2 servers. Its very vanilla, where players are going off in groups of 1 to 2 people and by luck or the hand of god are breaking through lines.
I hate squad leader spawns. As much as I hate to put it like that, but when you are trying to press an advantage, one man bailing out of a jeep in the sector will spawn in a whole crowd of reinforcements rendering your hard won minor victory void.
A whole array of things.