The League System
Has been and will continue to be terrible in its current iteration.
ELO was more balanced because you could go up incredibly high with a 10 win streak
and go down really low with a 10 loss streak
it punished people for continuous poor play.
The new system babies people way too much in the lower stretches while also hampering good players because it requires godlike win percentages to advance promos in a consistent manner.
overall I feel the league system has/will be inadequate compared to ELO.