This is it.
The only Stat we should care about for team games is top 200 vs 200 AT ONLY. Anything else is open to many more factors than a balanced AT match.
However:
1) Not that many people play AT v Random (would like to see some stats on that if we can get them)
Yes ok the usual suspects will drive by and say "Get friends noob" but that's beside the point. But then you are in "Just about any game is fun if played with friends" territory, says nothing about the quality or balance of the game
2) Of those that do play AT, they don't always play with the same people and don't necessarily get ranked.
You may check my player card for evidence of this.
Despite all my 4v4 games I am ranked with I believe only two teams
3) The great advantage of AT over random means the win proportion for AT is very high
4) As a result of all the above you can break top 200 AT on or soon after your tenth game.
I know that, because I've done it
5) AT has access to synergies that don't work in random, and are essentially fringe "exploits" <Cough - fuel drop cough>
So, if the idea is to balance around the best players, you won't get them in 4v4 AT, because I will estimate that 95% of getting ranked as 4v4 AT is playing lots of games rather than anything else