Getting put with plat 5 member
So I was playing a game with my friend. I'm lvl 23 and was going as Jax against a Zed. He pretty much had me at tower all game. After the game (which we lost) we saw he was in plat five. My friend is silver 5 and I'm only lvl 23! What's up with that? Does anyone know how I could get put with a plat 5 member?