There is only one kind of damage "redirection" mechanic always assured to be available. (Decoy drones don't count as they are not always available), forcefields. As such, this gives over-emphasis to the roles of forcefield giving units/strucutres and forcefield immune units.
Well, there's also Armor.
Also off the top of my head -
On the "sometimes" front, there are Decoy Drones, Attractors, Neinzul Scapegoats, Regen Golems, Champion Decoys (Sort-of: Armor Booster)
On the "Other ways to not die from damage" side, there's repair (Engineers, MSDs, ZMedics) and Regeneration (ZHydras, etc)
For 'Anti-' abilities, we have Armor Piercing. Decoys, Scapegoats, Repairing, and Regeneration have no counters.
For Forcefields, we have:
Always: FF Generators, HFFs, Riot Starships
Sometimes: Shieldbearers, Spirecraft Shieldbearers, Modular Fortresses (1-4 types), Champions/Nemesis, Spire Corvettes, Spire Capital ships (Destroyer up), Hybrids, Spire Shield Guardposts, Protector Starships, Avenger
Anti-FF: Raid Starships, Infiltrators, Zevastators, EyeBot
Sort-of-Anti-FF: Plasma Siege Starships, ZSiege, Champion Plasma Cannon modules, Spire Blade Spawner, Cutlass, Vampire, Viral Shredder, MiniRam, Ram, Maw
So, Yeah, there's a lot more Forcefield stuff available or likely to be available. But at the same time, there's a lot more FF Immune stuff (I know I missed some). Instead, I think Qatu calls it:
I though the problem is that overlapping ships with overlapping shields means all ships are protected by all shields. So while moving as a group if there's 500 bombers and 200 shields then the bombers cant be hurt until all 200 shields are beaten.
As long as it is so easy to have Forcefields mutually protect each other, while Armor can't help others, the Forcefields will be significantly more powerful.
An interest fix would be to say that no Forcefield generator could move within the bounds of another forcefield. That'd turn it from stacks to bubble clumps, which would at least be workable.