• Maybe I can use a more elaborate example. Assuming the following situation where each of the 5 coalition has 5 players:

Coalition A with 300 points

Coalition B with 200 points

Coalition C with 150 points

Coalition D with 100 points

Coalition E with 74 points

If you have 67 points, you will be in the 4th place. Because your weighted score (67/1000 = 0.0670) is greater than coalition D's weighted score (100/1500 = 0.0667). If you have 66 points, you will be in the 5th place.

Similarly, if you have 50 points, you will be in the 5th place. If you have 49 points, you will be in the 6th place.

I am not 100% sure that I did the math correctly. The easiest way to check is to log in to the game on the computer (I cant find it on mobile) and you will see your actual rank in the top left corner.

EDIT to add the following regarding the 2nd part of your question regarding the top guy leaving the coalition:
It depends on how many points the top guy has. You have to do the math...

Any sufficiently advanced tactic is indistinguishable from magic to the uninitiated.