@Yegg on topic.
Of course, it could always be a coincidence, but I noticed a change immediately. Specifically, I had been stuck in a pattern of being promoted (successfully completing the series) and then being bounced back down within 3-5 games. (2-3 losses).
The difference in the types of games before and after promotion was insane. The promotion games were "better than average" team quality, and post promotion seemed to inevitably include afks, trolls, or other problematic teammates.
After the hot-fix, I was promoted again (for the 8th time!) and the matches post-promotion were qualitatively different. The result was that I was able to stabilize in the new grouping. Don't know if this is some subtle effect of the changes, but after 7 cycles of promote / demote, the change is certainly welcome....