I would say it's a combination of various factors, JW Broadcasting being one of them
I would say these are the main reasons:
1. JW Broadcasting (JW's have been condemning TV evangelists for so many years but are now joining them? WTF???)
2. 1914, the supposed 100th year of Jesus's reign in heaven, came & went by uneventfully. Many had expectations that Armageddon was going to come, it was even suggested that we might have our last memorial that year in one of the OKM's. When nothing happened that year, many got fed up of waiting for the end & left / faded (Proverbs 13:12 - Expectation postponed makes the heart sick)
3. Candace Conti. Blew the child abuse issue in the org wide open! (The ARC came much later, the full impact of that would be seen in the 2016 report)
Other reasons:
4. An increasing number of people going online & stumbling across something which caused them to think / question (I was one of them)
5. Anthony Morris & his senseless rants (eg. tight pants)
6. Stephen Lett (more evidence for 1914 than for gravity, electricity, wind!)