head to head
Call of Duty: Modern Warfare 2 asks more than Brawl Stars, and the gap is execution.

Execution · Competitive PvP
Supercell's snappy top-down team brawler built around three-minute objective fights.

Execution · Competitive PvP
Blockbuster 2009 sequel famous for killstreak chains and frantic multiplayer.
Brawl Stars leans Execution (Competitive PvP); Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP).
Call of Duty: Modern Warfare 2 leans clearly harder on execution.
Brawl Stars
Aim, dodging, and ability timing in real time
Call of Duty: Modern Warfare 2
Fast time-to-kill rewards raw aim and reflex
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Brawl Stars
Human teams rotate, bait supers, and adapt
Call of Duty: Modern Warfare 2
Outguessing human rotations and flanks
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Brawl Stars
Bush ambushes and power-cube spawns hide information
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Brawl Stars
Brawler matchups and map strategy are learnable
Call of Duty: Modern Warfare 2
Killstreak economy, loadout and map knowledge
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.