First off, I want to thank the devs for their constant effort to make this game better. They only have the ability to make broad strokes and anything that makes the game better, I am 100% behind.
The reason why people quit/surrender in a match is because they are not having fun or see no way of winning. If my team is getting destroyed, why would I want to stick around? I think a way to fix the issue of a game snowballing out of control is rebalancing after half way through a match.
In meltdown, make it a bit harder when one team’s grinder has moved while the other’s have not. Maybe make an extra buildable available during that time or reduce the cost of giant minions until for losing team until they hit 250.
In incursion, make the buildables cost advanced PvE levels when in the opponents base.
Capture is great, but maybe reduce the cost of the accelerators for losing team when down by 500.
I have made a post before with diminishing returns on feeders so one team is not so over leveled and I still believe that needs to happen too.