A theory about Masters is that the system was broken (
@clickhappier first mentioned it). Looking back over past numbers, from 5/12/14 => 5/6/15: 899 masters added through 6 give outs. This put the current 989 given out in the same range for Masters/time. What looks like could have happened was that whatever system was used to select Masters was working, but the system to hand it out was broken, so people were just being added to the pool. Then it got fixed, and all of those people in the pool were given Masters thus accounting for the large sum of people who were given the qual at once, but for how much time has passed since the last time, that number falls in line with the average. This would not be the first time mturk broke something so its not out of the realm of possibility.
also