Since *pro* groups can't list in single queues, because those are ""SINGLE"" queues, which pro groups don't linke, since - well - they are s--i--n--g--l--e , you won't find many pvp players listing for those. In addition to that. Casual players won't list too, neither for single, nor group queues, because there are way too many pro pvp players, steam rolling them. That is something those players do not like and want. They have other/better things to spent their play time on .
If you want shorter queue times, you will need to find a way to balance the pvp part of the game in a way so that casual players will start playing more pvp. The problem here is, that if you will try to do something like this, you will anger the pro pvp players, which will cry out and stop playing . You see/notice the predicament?!