The lobby isnt really meant for balanced games. It is more for things like playing with friends in premades teams, tournament games, community games, … Stuff like that.
Ranked is made for balanced games, even if you consider yourself a noob. You need some games before the system knows your strength and you will get balanced games.
Current issues in the match making / ratings of match making are already discussed in other threads, like Analyses of the ratings - Spotting the issues
Some adjustments to the rating system are already posted in that thread. On of them is the Glicko-2 system. I would suggest you to have a read of that thread and comment your opinion in that thread as well.
Not sure what you meant, but unranked rating is based on all games in the lobby not containing an AI as player.