The reason that Frontlines is awful is that there is no such thing as a 3 sided battle. Even in actual matches, conflicts are largely fought between two different factions and the third is just kind of winging it because ultimately each side has to choose which side they are fighting. If one side just splits to fight both sides equally, they risk taking the heat of both other factions and getting annihilated.
I can understand the idea that people want to keep a weird goofy mode around for the point of it supposedly being idealistically more random than a two sided fight and therefore more beginner friendly, but that isn't how it plays out. They even shuffle teams around to try and randomize things and it still turns into a two sided conflict where one faction is going to get beaten down to the floor each time. Actually, I did some digging and the closest thing I could find in real life of a three way fight was the invasion of England in 1066 where it was Norway, Normandy, and the Anglo-Saxons. The Anglo-Saxons and Norwegians clashed at Stamford Bridge which the Anglo-Saxons won. The Normans then wiped up the weakened Anglo-Saxons, leading to modern England.
This entire process plays out in Frontlines just like the war of 1066. Two sides fight, one side wins, the third side that wasn't involved wipes out the side that won, and then it just comes down to how well the two sides that were wiped out can organize. And that is the best case scenario because what also happens in Frontlines is that two sides are basically unspoken allies and simply work together as one big team. This seems to happen on aether a lot and they just beat down the other side until they are practically on the spawn point until they cap enough points where they don't need to suppress the other side. The two sides that are allied then just decide who gets first and second.
There is no actual way to improve frontlines. They already tried to fix it with randomizing teams and which faction someone gets on but it doesn't work and the problems go beyond the design of pvp actions. By the way, it is universally easier to identify someone trying to fix a match in a two way fight than in Frontlines. Just have to look at what people are doing... and not doing.