Get rid of ELO. Get a TrueSkill system.
The system of ELO ranking is so broke, especially with 2/3 and 3/5 series matches. You can't control the team you get, and we all have seen games where one player single-handedly will carry his entire team to a win. Why do his teammates deserve as much LP as him? We all have games with trolls where when their pick rolls around and ADC is left open they choose to try and duo mid as if it was their right. If you're not able to carry one or two bad players, as much of a team game as this is, you shouldn't be slammed with a hard LP loss because you didn't want to surrender in a ranked game.
This takes me back to when I used to play Halo 3 all day long, 4 seasons straight. They had a system, which is patented by Microsoft called, the TrueSkill System. In a sense, every game you play, a program takes in how well you do, if you win or lose, the ranks of everyone on your team and compares them with the ranks of the other team. So if you have a team that's really good, let's say a team where everyone is in Gold, versus a team where everyone is in bronze, the bronze team off the bat will not lose as much LP as they would versus another bronze team, and if someone on that bronze team goes 15-0, they might actually gain LP, seeing as how they went against a much harder foe and managed to come out with a good score.
The only reason I can understand the logic behind the current ELO system is that old tiresome argument of, "it's a team game, and if you can't help your team win, you deserve to lose." If someone consistently is playing well, they deserve to rank up.