The current ranking system does not seem successful to me. That is, for a well-coordinated regular team game, it is probably suitable, but for all the others it is not very. Too many factors of luck influence the result. And here the reason is primarily in the genre and key mechanics. And losing points due to the fact that no luck is very unpleasant, as well as winning because of the fact that just lucky is not very interesting.
I would suggest adding a third mode. Use the system of elite matches from the last event and turn it into an analogue of the king of the hill. For example, everyone starts on bronze 4, those who hit the top 5 go to bronze 3, all those who did not get back to bronze 4, and so on.
In order to reduce the likelihood of a camper, you can add a condition of three killings to a squad when reaching the top 5. That is, a squad must not only enter the top 5 but also defeat at least one enemy squad. For the top 2 and the winners, this restriction can be removed as I have already been in a situation when not one opponent met my squad before the final battle, where we won by making only two frags in a fight with two squads.
As for waiting for the selection of players in high ranks. Allow players to lower the rank when waiting in the lobby for longer than a certain time, for example, one and a half minutes.