Changes to farming [Heavy Junkbox] in prepatch?

Before the prepatch, I started The Insane grind and I was down to DMF and farming boxes, and I would make tons of class trial rogues to farm the junkboxes, and I’d average a little more than 2 a minute, so in an hour I’d have roughly 120-40. Well, since prepatch hit I just levelled a rogue to 50, and I started back up on my grind, and the drop rate was abysmal, like I farmed the same spot for about 5 minutes and didn’t get a single drop! What gives?