I love TT and I play it as often as SR and CS. Here's the meta in a nutshell, if that nutshell was big and wordy and not worth reading:
Players pick from a limited menu of champs. In every game, at least 3 of 6 will be playing:
Cait, Fiddle, Jax, Lee Sin, Yi, Panth, Shaco, Teemo, Tryn, Twitch, or WW
But you will also see a lot of: Mundo, Ez, Poppy, Singed, Vayne, and Xin
If u pick anyone else and u will get reported by your teammates for intentional feeding before you even buy your gear.
phase 1: Everyone runs to bot mid bush and have an absurd lvl1 teamfight.
phase 2: after that fight, the teams splits into a solotop + a duobot with everyone participating in ganks.
I'm not sure why it's not the reverse, since top lane has reach to all the buffs and bot is less gankable since it can only be attacked from above.
phase 3: losing team hides behind 2nd turret, while winning team has a monopoly on jungle and feeds and wards. Then they make a big Disney movie style comeback or die trying.
EDIT: olaf, corki, and occasionally gragas get some play too