Placement Matchmaking?

[Kamikaze28]

The goal of placement matches is to gauge your skill. Since the system is comparative out of necessity, the best results come from games against players with known skill.
While your opponents may not have been ranked yet, the system may have already known their skill to a certain degree (there were two league resets shortly after launch). Losing against a Master or Super-Titan skilled players is hardly surprising and the only conclusion for the system is, that this new player must a lower skill level than a Master or Super-Titan League player.
While you keep playing, the system will get a more accurate sense for your skill and will promote and demote you accordingly. So while your initial placement may displease you, time and patience will fix it.