head to head
Neither is simply harder - they are hard in different places. Injustice 2 demands more reads; StarCraft demands more optimization.

Execution · Grand Arena
A superhero fighter with gear-based customisation where execution and opponent reads sit atop a deep optimisation layer.

Optimization · Grand Arena
A real-time strategy classic where perfected build orders and mechanical speed decide most matches.
Injustice 2 leans Execution (Grand Arena); StarCraft leans Optimization (Grand Arena).
Injustice 2 leans a little harder on execution, though the gap is small.
Injustice 2
Supermove confirms and precise character-specific combos demand execution
StarCraft
APM and micro control ceiling is huge
Injustice 2 leans clearly harder on reads.
Injustice 2
Meter burn mix-ups and opponent tendency tracking are constant
StarCraft
scouting and predicting human opponent builds
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Injustice 2
No RNG; transparent match states
StarCraft
minimal hidden info beyond fog of war
StarCraft leans clearly harder on optimization.
Injustice 2
Gear stat distribution and character sub-archetype selection reward planning
StarCraft
build orders and economy are near-solvable
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.