Hey, I believe the best way to fix the balancing issues in Battlegrounds is pretty simple. The main problem is that Team A often has a significant advantage, which causes Team B to leave the match. This usually happens due to bad matchmaking or Team A having more healers. Even with the healer balancing system in place, there are times when a healer might miss the queue or leave, resulting in situations where it feels like it's 3 vs 1 or 2 vs 1 in terms of healers. Additionally, players sometimes leave or go AFK during the match, which makes it even harder for the losing team to catch up. By the time new players join, it's often too late to make a difference in points. A good solution could be to introduce a buff called Tenacity in Battlegrounds. This buff would increase health, healing, health regeneration, and damage dealt, and it would stack based on how outnumbered your team is. So, if the match is unfair, like 10 vs 6, the smaller team would still have a fighting chance with this buff. Plus, this isn't a new idea; this buff already exists in the game from the Wintergrasp battle in WotLK, so it would just need to be applied to Battlegrounds.
https://www.wowhead.com/wotlk/spell=58549/tenacity