Are the specific actual rules of the Rank Meter known?

Regarding the Rank Meter in Ranked in Splatoon 2,

Here's the problem:

1. Say you have one or two cracks. In fact, sometimes when you lose a match, it does not give another crack.

2. Indeed sometimes when you are are on three cracks and you lose, it does not demote/pushback...you seem to get one more free chance.

(Note, I mean in normal games with no disconnects. Of course, when there's a disconnect you are not penalized.)

3. Moreover, when you win the amount of movement to the right seems to vary. Sometimes a little, sometimes a lot.

4. It does not seem to relate to your personal performance in the game (whether number of kills, coverage, time in control etc).

Does anyone know what the actual exact rules are for

(1) When or if you get a crack

(2) How much it moves when you win

It genuinely seems somewhat random.

I checked the printed handbook and it has no information.