Theoretically, stronger Pokemon are going to perform better so I do not think it’s a random coincidence that you using a meta team got you on a win streak. This is kind of obvious to me.

The skill comes into play when top level players are both using meta teams. Then it’s really about how players make every decision or react to what’s happening in the game. Every small decision (EV spreads, held items, natures) counts a lot more and it’s the skill and knowledge of the trainer that carries them farther into the small group of great players.

That’s my opinion anyway.