Its so blatantly rigged it blows my mind. Playing 2 games as the panda hero. It consistently offers the worst hero powers in the game such as Edvins, Cariel, Kitty and Nozdormu. No way that shit is random. Its scripted.
Extremely rare to get Reno for example on that hero.
I have played since early beta. I have almost 1000 hours sunk in this mode. I wanted to share my observation of the course of the years.
Battleground features heavily predetermined mmr brackets. Once you hit yours, (for me its around 6000) it becomes impossible to climb. The points you get for winning are so low compared to the points you lose. This is on purpose.
There are other ways the system screws you over as well. Last game I was playing patches. Game lasted quite a long time. I didn't get a single triple. What are the odds of that as patches? Very, very, low.
The way the system favors a winner is by allotting triples. This is NOT random in my observation. I also suspect it can read your board state and heavily favor certain units and tribes as well. I have found that if you intentionally concede a bunch of games you suddenly start to get more favorable matches.
Another blatant example of rigging is fighting ghosts. If I am on a big win streak and in my predetermined mmr-bracket then the system will do its best to avoid giving me a ghost fight. Some games it borders the absurd. I can be losing 5-6 fights in a row, and still it refuses to let me play the ghost.
If you want to enjoy BG, accept it for what it is, a rigged slot machine. If you attempt to climb you are in for a really miserable time. Instead, just concede a bunch of games when you hit your MMR-ceiling and focus on just having fun.