Look, it's fairly simple. What you've got going is a positive feedback loop, which, despite the name, is very FUCKING BAD.

Losing a game in crucible? Ok just leave. There's literally no point in sticking around, since you'll go 3 games in a row where you get 0 rewards and the lowest K/D player on your team gets 49 strange coins and a letter from the President.

What you need is less RNG to reward the top players to stay, and more punishment to the players who are leaving.

PLEASE BUNGO, give us a reason to finish the game. I'm even admitting it myself, I'm part of the problem; but I'm only abusing a system you've enabled. Fix it. Reward players for playing the game.