Right now there is no team shuffle if you join lobby. I dont see it as a viable solution anyway.
There is also a high chance that players who saw that their team could not handle it and left.
I honestly leave those lobbys myself, beacause I often play different heroes and would like to
get more balanced match. 1 out of 4 lobbys joined has potential to be fair.
Of course the MM is terrible, but join in lobby is even worse.
Perhaps just rework join in lobby, cuz those 3 times out of 4 my teammates were very low prestige
or none at all while opponents often had 2 players with prestige 10+.