Iam not sure how the current matchmaking work but its not about card lvls for sure.
If you are half lvl 1-2 cards against someone with full lvl 3 cards your not gonna have a decent match, kids lvl dont matter this much you only get hp and +1 or 2 attack but cards lvl matters ALOT.
If you could take a look at this, it would make the pvp more balanced for everyone and the new ppl that will try your game in the coming months.