I hear ya man, I hate when that happens too 
Iāve pitched the idea of simply replacing bg leavers with generic Blizzard AI bots in the feedback thread, my idea would effectively END this annoying problem of getting backfilled into losing bgs for good. With AI bot backfillers we would be GUARANTEED a fresh match every time we queue up for a bg.
Hereās a link to the discussion: Feedback: Epic Battlegrounds - #1026 by Gdtroll-illidan
Maybe you should go there and drop a reply in support of my idea? 
The devs actually read that thread, so youāre just wasting your time with this thread to be honestā¦ gotta post in āfeedbackā threads to be seen or noticed
I feel ya on this issue, getting backfilled into losing bgs is a big pet-peeve of mine 