i have been playing BG more than a year and last month are horrible in terms of grouping.
My daily routine is wirts, daily quest and 1 round of BG match with my pvp char. More than 3 months i never played in a BG match that has full 12 players.
It's mostly 4vs3v3, commonly 4vs4vs3, more than 30% is 4vs3vs2 or 4vs2vs2 i think you guys get the point.
today i played 7 or 8 times and never played in a match with 12 players again. 2 times i ended up in a 4vs2vs2 situation.
i dont know how to solve this but i think maybe limiting BG group with 3 people will help, at least 2vs3 is better than 2vs4.