For the second year in a row, NFL ratings have taken a slight tumble. Through the first seven weeks of the season, TV viewership is down roughly 5 percent from the same point of the 2016 season and about 18 percent from the same period of the 2015 season.

Although there have been a lot of theories on why the NFL's TV numbers have tumbled -- from Donald Trump to national anthem protesters to Roger Goodell feuding with players -- Fox chief executive officer James Murdoch isn't buying into any of them.

Murdoch, who spoke at the Paley International Council Summit in New York on Wednesday, said he believes ratings are down because there's an "overproliferation" of football. Basically, there are so many opportunities for fans to watch games that the market is now oversaturated.

"There's a question mark for the NFL, which is just to think hard about how they're licensing," Murdoch said, via Ad Week. "So I do think the proliferation of Thursday availability -- and the proliferation of football generally -- does mean that you're asking a lot from customers to watch Thursday. And then they watch a lot more college football game on Saturdays, and then on Sundays, and then on "Monday Night Football," etc. It's a lot. So I do think that preserving the scarcity value of those events and that audience is something that is worth thinking about."

NBC Sports chairman Mark Lazarus echoed that sentiment during a recent interview with the Sports Business Journal.

"I do believe that there is a lot of football on and by the time you get to Sunday, there could be a fatigue," Lazarus said. "Much of the loss of viewers is coming from 18-to-34-year-olds. They more and more are getting satisfied by the alternatives of highlights and scores that are available during the game. That continues to train young viewers to follow our sports, not watch our sports. That is concerning for all sports television."

Although we now see Sunday, Monday and Thursday games every week, it hasn't always been that way. Before 1987, there were really only three game windows: 1 p.m. ET and 4 p.m. ET on Sunday plus Monday night.

Over the past 30 years, the NFL has steadily added more viewing windows. Thursday football went from a novelty that was only played on Thanksgiving to a weekly fixture on the schedule. The league also added "Sunday Night Football" and a fourth viewing window on Sundays with the addition of a 9:30 a.m. game in London. Not to mention, there's also the occasional Saturday game.

Three years ago, one person actually predicted that the NFL would take a tumble in the near future. In 2014, Dallas Mavericks owner Mark Cuban made some interesting comments after the NFL decided to move the "Thursday Night Football" package to network TV.

"I think the NFL is 10 years away from an implosion," Cuban said at the time. "I'm just telling you, pigs get fat, hogs get slaughtered. And they're getting hoggy. Just watch. Pigs get fat, hogs get slaughtered. When you try to take it too far, people turn the other way. I'm just telling you, when you've got a good thing and you get greedy, it always, always, always, always, always turns on you. That's rule number one of business."

Three years later, it appears that network executives like Murdoch might be heeding Cuban's warning. According to the Sports Business Journal, "media executives and some sponsors" have asked the league to trim the Thursday night package back to eight games. Executives are also reportedly ask the NFL to dump the 9:30 a.m. ET window for London games.