Ur matched against teams according to ur Personal Rating and not ur Team Rating, so if u disband a team with 2000 personal rating, u will face 2000 rated team even with ur team rating at 1500.

What some ppl do, just to showoff the team rating is making a 5v5 team and sink it to 1200 or 1300 and then rejoin a team of 1800+. Then u'll be queued against low rated teams on a high rated team. So u see, it's ur personal rating that tells who u are: it matches ur opponents, and it tell what gear u can or cant have. U can't buy items with the team rating, but instead with ur personal rating.
Out of curiosity, there was a guy bashing me the other day, saying mb sucks and that i sucked. Hes team rating was 1800+, but with an addon i was able to see that his PR was 1500 with more losses than wins :P PR does in fact tells what kind of player u are, unless ur playing at 5 am
Feel free to delete the post if u dont like these things discussed, but, its something thats exists, that blizzard is aware of.
If u have a team member rated 100 lower than ur personal rating, u'll face a team that matches the lowest PR. Correct me if im wrong.