Prior to build 9014, if you cast Shadow Word:Pain while using a trinket or some other damage boosting ability (as I mentioned with the old Dispersion mechanic), when you refreshed SW:P by casting Mind Flay (with the Pain and Suffering ability), your SW:P would carry that boosted/trinketed damage the entire fight, or until you manually refreshed it.
Build 9014 changed that. Now, when you refresh SW:P by manually casting it or by refreshing it with Mind Flay, the SW:P ticks are recalculated. So if you pop a trinket, cast SW:P, when the trinket wears off, the SW:P ticks will continue at their trinketed damage level until you cast Mind Flay.
This isn’t really a nerf, though – it’s a bug fix.