Many reasons why. One of the main reasons involves Lebron James and others who backed China who is invading Hong Kong and other countries. China does so many bad things. So, when you go to an NBA game in the United States with a Free Hong Kong sign, they will kick you out. Other reasons involves people simply watching other things and doing other things. There is more competition out there and only so many hours in the day to watch things. Plus, some people may watch the NBA via YouTube, etc. That means that the rating count may not accurately reflect all of that. The NBA has an official channel on YouTube for example. But, you see, they're not the only ones with basketball channels. And there are other websites, etc.