Noting there are some issues with specific battleground formats which are well covered in other threads, I think the matchmaking has broadly improved battlegrounds. However with each game being independent there is still a problem that there isn't a longer term motivation to do well, because the better you do the worse teammates or harder opponents you get, so overall every game feels about as hard as every other game.

What if there were campaigns? Here's how it could work:

• At the tart of each month you get randomly assigned to either Storm Lords, Pit Daemons or Fire Drakes.
• Solo battleground matchmaking works in the same way that it does currently, except that when assigning a battleground two of the three teams are picked randomly, and players belonging to those teams are assigned to the sides according to their MMR.
• Games proceed as normal.
• Teams form a leaderboard according to total medal score. (By doing it based on total medal score rather than win / loss it means you can feel like you're contributing to the team's campaign performance by earning medals even when you're getting beaten overall in a game.)
• At the end of the campaign you get end of campaign rewards depending on how your team performed.
• For the next campaign the team assignments are re-randomized at the same time the MMR ratings are reset.

This would also have the benefit of restoring the Storm Lords team, who are sadly missed. I guess there would be a small impact on queue time, but really the queues are pretty short anyway and hopefully the added motivation from team ethos might encourage more players to take up the play style (that's the whole point after all...)

Note this suggestion is probably just for solo BG queues as it feels like a difficult problem to ensure that all of a group of regular BG teammates end up on the same team.