For what it's worth, one of the beat writers had this to say:

Mark Kaboly@MarkKaboly_Trib#Steelers LaMarr Woodley's weight had nothing to do with his dropoff. Quick throws and dropping into coverage more b/c Harrison couldn't did
I don't agree with this premise in the least. Watching Woodley, it was clear that he was not an explosive player off the edge as he had been in past seasons.