head to head
Call of Duty: Modern Warfare 2 asks more than Mortal Kombat Trilogy, and the gap is variance.

Execution · Competitive PvP
Blockbuster 2009 sequel famous for killstreak chains and frantic multiplayer.

Execution · Competitive PvP
Classic fighting execution and human prediction atop a famously unbalanced roster.
Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP); Mortal Kombat Trilogy leans Execution (Competitive PvP).
Call of Duty: Modern Warfare 2 leans a little harder on execution, though the gap is small.
Call of Duty: Modern Warfare 2
Fast time-to-kill rewards raw aim and reflex
Mortal Kombat Trilogy
Dial-a-combo inputs and run-meter pressure demand fast hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare 2
Outguessing human rotations and flanks
Mortal Kombat Trilogy
Human opponents must be baited into unsafe moves
Call of Duty: Modern Warfare 2 leans clearly harder on variance.
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
Mortal Kombat Trilogy
Movesets are public; nothing hidden in a match
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare 2
Killstreak economy, loadout and map knowledge
Mortal Kombat Trilogy
Knowing the bloated roster's broken tech is half the battle
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.