Things like aim/movement fall into the grey area between mechanics and fundamentals. Raw aim = mechanics. Crosshair placement = fundamentals. Basic Movement

Things like aim/movement fall into the grey area between mechanics and fundamentals. Raw aim = mechanics. Crosshair placement = fundamentals. Basic Movement = mechanics. Pathing = fundamentals. You're absolutely right about things just being hard though. The gaps between even professional players can be huge in one area and nonexistent in another. Once you take that and apply it at the team level, it's easy to understand why a player could shine among a certain group, and do terribly with another, even if both groups were of very similar 'skill.'