I think a bigger problem is how it interacts with tb. Tb encouraged us to farm and level trash toons to get stars. Now all the trash we have counts for our active gp even if our effective gp (that is the gp of the toons that meet the 6k requirement & can actually do offense/defense) is significantly lower.
In that case a 25 v 50 can be favorable to the 50 who can zerg rush their opponents who might have slightly higher teams but barring a top 20 arena team are still likely killable if you throw enough bodies at them.
Point being matchmaker needs an overhaul to take into acount more factors than active gp.