During GST, I think each team should have the chance to start on each side of the arena. And you can't proceed unless you win by 2 points like this you actual dominate starting on both sides.
If you guys think it would add much more time then I guess random queue for last round.

Second idea, have somewhat a class system:
So when building a team there could be 4 options for what a player would want to be
1. starts with 10 health and deals 1 damage per hit.
2. starts with 6-7 health but deals 1.5-1.75 damage per hit.
3. starts with 15 health but deals 0.75 damage per hit.
4. starts with 15 health doesn't deal damage but can go and hit one of his teammate and give him back 0.5-0.75 health.

Third idea, I already mentioned this before but semis and finals should have more rounds.

Thank you for reading.