There's no way all those people are leaving for streaming. I'll bet most of them are going to their cable provider who also provides their internet. That's why they are seeing much lower losses - they are picking up some of those who are leaving Directv over their promo prices ending etc.
When you measure Directv at $100+ after their promo expires versus adding TV to their cable broadband for less than half that due to bundling savings, it is a pretty easy decision for people who don't have a particular reason (i.e. NFLST) to stay with Directv. Especially with several high profile disputes over the summer stretching into the start of football season.