DQ has caused a shift in the player base, and quite a significant one.
http://www.leagueofgraphs.com/rankings/rank-distribution
Although I cannot see any immediate way to review older information, from what I can remember the player-base was distributed into the top 8.79% being in plat-challenger and the bottom 73.1% being in bronze-silver which leaves roughly 18.11% of the community in gold. Right now as you can see there has been an influx of players into platinum (myself included, soloQ for the win baby) and gold in particular with a .3%~ increase to diamond V. This is a total of 1% of players (roughly 1 million players) being injected into platinum, and close to 5-6% (5-6 million into gold.) What does this all mean? Well boosting as a whole is just rampant whether it be via illegal or payed measure or just friends helping out their lower skill buddies the results are evident. Dynamic queue has caused a general rank upset overall, and my recommendation is to introduce a much harder MMR reset to all players bronze-platinum at the end of this season, and the introduction of pure soloQ. We've gotten ranked teams, both 3v3 and 5v5 so the excuse of not having ranked to play with friends no longer holds water and can easily be dismissed. (Keep in mind team ranks have their own benefits and what not to those successful at playing with others.)
If someone can get me last season's information that would be fantastic, as it's far too late for me to think rationally and actually find it. (I'm going off mostly memory, but I do recall this as being accurate. If not, by all means correct me.