Dynamic queue placements
Since dynamic queue seems to be replacing the old ranked 5v5 teams, and there will be a dedicated true solo queue later on, I'm wondering what our starting MMR going into dynamic queue placements was actually based on. The vast majority of players seem to be finding themselves often a full tier below where they expected (often based on their season solo/duo queue rank), and while it's plausible that many players had a lower MMR then their rank would have indicated and that combined with the soft reset is a sufficient explanation, I wonder if there might be another explanation.
Is it possible that ones ranked 5v5 MMR is/was used to seed placements, rather than season 5 solo queue? I expect for the majority of players their 5v5 ranks were somewhat lower than their solo queue ones, with many players only playing enough team ranked to unlock the team specific (re)wards, if they played at all.
Does this explanation seem plausible to players? Any riot confirmation whether or not that was the case? Anyone out there who had a higher ranked 5v5 rank then their solo queue rank last season, who may have actually placed higher then expected after their placements? Or any other anecdotal evidence they might support/discredit this theory?