Demotion Logic... Fail.

You are at 0 LP. And then you lose and are demoted. (1 game - Loss)

Now you are at 75 LP. You lose again. (1 game - Loss)

Now you are at 50 LP. You lose again (1 game - Loss)

Now you are at 25 LP.

--- With 3 losses in a row you have been moved down nearly an entire tier ---

Now lets count how many it takes to get back up.

You are at 25 LP. You win. (1 game - Win)

You are at 50 LP. You win (1 game - Win)

You are at 75 LP. You win (1 game - Win)

You are in promotion. You win. (1 game - Win)

You are in promotion. You win. (1 game - Win)

-- A total of 5 games to get back to zero LP --

Conclusion: You need to win roughly 60% more games than y you lose to get back to where you were

Note: I am aware that you don't always get demoted instantly from 0 LP. But in my experience with 2k+ games over 3 seasons its a vast majority of the time that demotions have no buffer zone. Compare this to the always-present promotion system... Not balanced at all.