Yeah its level bracket based first, then based on W-L, then based on power from my experience. Thats why if you're in the level 90 bracket you will match those level 65s after a min and destroy them unfortunately.
If you're on your last team or just need 1 more to 5 wins, try asking in fight chat, never hurts hehe, the high power people normally have spare teams to retreat. I normally run a scrub team first for feeding purposes.
I really hope the window doesnt get shrunk though, Mondays and Fridays are more relaxing for this reason, where I can log on late, do 9 tails then start matsuri/TI after 9.