They just choose a random Champ and a random Adjective or something. But what I am saying though is they seperate the tons and tons of players that are in Silver Tier into groups of like 250. So I am in the group called Corki's Spellswords. The groups don't mean anything though, because its not like you only face those people. They just did it so you can visually see a smaller leaderboard, making it feel like you are actually ranking up. They also tried to make it so you are put into ones with your friends. So if all of us reached Gold, we would probably be in the same Tier that Vishra is in.