head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Grand Arena
A tag-assisted fighter blending execution with read-based mixups.

Execution · Grand Arena
Team hero shooter blending FPS mechanics with ability economy mind games.
Mortal Kombat 1 leans Execution (Grand Arena); Overwatch leans Execution (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Kombat 1
Kameo timing and combo execution gate damage.
Overwatch
Hero aim, movement, and ability timing
Mortal Kombat 1 leans a little harder on reads, though the gap is small.
Mortal Kombat 1
Adaptive opponents bait pokes and wakeups.
Overwatch
Ult tracking, flanks, and baiting human teams
Overwatch leans a little harder on variance, though the gap is small.
Mortal Kombat 1
Effectively no randomness in matches.
Overwatch
Minor spread and matchmaking noise
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Kombat 1
Kameo synergy, frame data, and punish theory.
Overwatch
Team comps, ult economy, and positioning theory
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.