I asked on the PVP forum; while I only got 3 replies, they all agreed that you just need to have 30% of the games played on a team that played 10 games, and not that each player needed to play 10 games as well.

http://forums.worldofwarcraft.com/thread.html?topicId=1134168180&sid=1

I don't know what happened to make it look like each player needed 10 games, maybe that was a bug that got fixed a while ago?