I wholeheartedly disagree to add penalties for leaving, introducing penalty for leaving will 100% make people not play it. I know that if the community playing control knew what makes a win (creates points fast) and they add a proper communication possibility for the full team it might change (not the 3 but the 9) or its going to be exactly as it is, it will not change in a week, or a year.
Right now we live in an extremely unstable situation with the gameclient, it crash ever 2-3 games you play. People when the client crash and they are one a team not playing the objectives properly will most likely just dont give a hoot about reconnecting. Problem is control dont teach the player how to win, what gives points when and it even credits the wrong tachtics esp for the loosing side. This is the base problem with the system as is. BR took 12 seasons to get a decent point system, Arena is strugling in a great way and control is no better off.
If you play control you play either for being able to hit the fray real fast or you wont be happy with the mode. To make it a viable competitive mode where people actually try hard they need to tweak the format and teach the masses or it will be going the way its going.
Edit: Yes they should let people choose if they queue for a game from start or any (even filler), it should be a choice at queue time. They should also look at their catchup mechanics, because now it credits the winning team not the loosing team, its a winning keep winning mechanic the bonus cap points :P...