They have definitely turned up the legendary drop chance last few days. In just 2 days we have gotten around 15 legendaries in our guild, 9 yesterday and 6 today. We have had groups farming +2 keystones constantly most evenings we have 3 or 4 groups farming +2's. Almost all the legendaries are from mythic+ chests.
We have had some people get 2 legendaries within hours of each other.