*ahem* SURPRISE! The first and possibly second week after everyone who pre-orders WoD gets their level boosts LFR is a mess.
Why would you assume that the trend would continue? There's no reason to. After the huge boost boom where you got a boost for preordering WoD, the number of boosts will be much smaller now. Yeah, LFR sucked for a week or two, worse than usual, but it WILL stabilize.