(1) Tactical air units (Wraiths, Mutas, Scouts) are weak against support air units (Valkyries, Devourers, Corsairs)
(2) Support air units are weak against capital ships (Battlecruisers, Carriers)
(3) Capital ships are weak against tactical air units
This is mostly correct except for Zerg, where the Scourge/Mutalisk/Devourer form an interesting combination
* Mutalisk: Generally frail in any A2A matchup except in ZvZ
* Scourge: Generally strong in small numbers, useful for sniping capital ships and expensive units
* Devourer: Strong against almost ALL air units (weird)
Now, during the 10+ years of StarCraft pro-gaming scene this model has shown lots of problems. Because air units are only used situationally (again, excluding vs Zerg), Valkyries, Corsairs, and Devourers have little use in most cases. I think SC2 solves this problem nicely -- the A2A units (Viking, Phoenix, Corruptor) have some means of helping ground armies (through transformation, Gravitron Beam, and Corruption / morph to Brood Lords). This is all fine, but merely copying them wouldn't be fun.
So in what ways could the three units, Corsair, Valkyrie, Devourer, could be improved so that they get to be used in any game? Obviously, this is NOT about making them stronger, it's about giving them means of supporting ground forces.
Suggestion 1: Give them a ground attack
Answer: The worst possible measure. First of all, it's boring to have more all-around units. See how Blizzard is mucking around with the new Tempest in HoTS? Yeah, that shouldn't have happened.
Suggestion 2: Give them special abilities.
Answer: Most plausible. But what?
2-1: Reduce Disruption Web research cost and energy req
This is the most realistic & unintrusive change I think. I think Corsairs should be pretty useful in PvT with this change. Maybe reduce the range to 3~5 so that enemies have a chance to EMP/snipe the Corsair before it casts D-Web.
2-1: Suicidal explosion dealing splash damage
Thematically, this fits the Zerg Devourer, as only a hive mind could consider sacrificing individual units for the sake of the army. The only problem is that with its large costs and huge HP pool, it will be impossible to shoot down incoming Devourers...meaning that they will either be way OP or super useless.
2-2: Separate the Corrosive Acid effect into a separate spell that affects ground and air
It works, but that makes the Devourer a Corruptor-clone. Besides I think a 9-Acid Spores stack on ground units is going to be way OP.
2-3: Just make the Corrosive Acid effect (not damage) splash onto ground units as well
Better than the above, but still the balance stuff....maybe reduce the maximum stack level to 3 to compensate?
2-4: Salvage (i.e. SC2 Bunker) for Valkyries / Devourers
Thematically, this should fit Terrans, but the question is: Why Valkyries only? Then you start giving salvage to BCs, Wraiths, SVs, Dropships, etc. and things go crazy from there.
Same for Zerg Devourers.
2-5: Give Spider Mines to Valkyries
I actually tried this in a SC1 to SC2 mod a long time ago. Looking back, it was a lame attempt to recreate the SC2 Viking. Crappy.
So...any ideas? Let's brainstorm.
None.