Ya matching should be done by role and not the team collectively.
New dps vs new dps
amazing healer vs amazing healer
Also The way WoW handles long ques is that the longer a que gets the more likely it compensate by matching you vs people who are lower rated than you. Obviously should the person who's role rating is lower than the counterpart loses less rating while the person with the higher rating stands to lose more rating than normal if they lose.
SE needs to get away from this constant +25 -25 type system, just reaffirms that matchmaking has a lot of luck mixed in that tries to make every single match a 50/50 chance of loss or victory
