From current patch notes:
Quitting a Battleground before it's over will now result in a 5 minute penalty instead of 20 minutes.
Seriously, plenty of people already quit right away the second they die, get steam rolled, decide during the first minute they can't win , whatever and now your giving them even more incentive to do just that. Most matches already end with less than full teams except for the one that is winning as it is. This is just going to encourage people to quit even more instead of trying to fight it out. Please, we need more incentives to stay for the losing teams, not less.