I played a few rounds and i dont get what should be balanced about this.
Totaly random teams of which the one with better random heroes wins, at least in SD you could talk with your teammates and pick a team with good combos.
When you want to add an unbalanced complety random mode, i dont mind but at least keep SD.
You could also show the other teams picks in SD if you want a fairer match, so that the other team can counter some heroes.