I dunno about high ELO,
but in low ELO, you're either a good player or a bad player. If you're a bad player, your only job is to make sure everyone you play with stays in your ELO. If you're a good player, all you have to do is pray those bad players aren't on your team.
Sorry if I'm venting, but
If you're kicking ass as Malphite jungle, and your Jinx goes 0/12/4, split pushes and feeds all game long,
and she says, "I might be 0/12, but you're going attack speed malph!!!!! you're the bad player!!!!!!!!!"
It really makes me wish I could start in a higher ELO, like Plat. If I truly wasn't plat material, I'd drop back down to gold. Oh well. But at least I wouldn't CONSTANTLY get utter shit, garbage teammates that feed in the early game and make it impossible for anyone else to ever get a kill after the snowballing starts.