From everything I have seen they matchmake based on your emblem choice. I know there aren't a lot of choices, but I run the eagle and I ALWAYS have another eagle with me. My buddy runs howling wolf, and surprise there's always another howling wolf in our squid.
This remains true after changing the emblem too. Squad always has matching.
In reality though I have no idea what they use for matchmaking but it's busted. Most of my games are stomps one way or the other. 1 in maybe 5-6 are an actual battle. I'm not sure if the system is busted or maybe the botfarming broke something, but it's bad.