The Vikings will play in primetime for the second time in four weeks when they take on the Giants in Monday Night Football. When they do, there's a good chance fewer people than we've come to expect will be watching.

That's because viewership for many live sports events — including primetime NFL games — is down considerably this year, per a look at the numbers by Sports Business Daily.

Some of the data, per the story:

"Sunday Night Football," television's highest-rated prime-time show for five years running, has seen a 10 percent viewership drop so far this season. Cable's top sports property, "Monday Night Football," is down 19 percent — the series' slowest start in a decade. Through two games, "Thursday Night Football" viewership is down 15 percent.

Now, this of course comes on the heels of massive growth over the past decade. Even small double-digit drops in viewership in those three areas (in a small sample size, it should also be noted) still mean the NFL is wildly popular.

Analysts say it's not time to panic and offer a variety of theories — including the migration to digital platforms and the fact that this is just a strange year and sports are caught in a particular cycle. And it is also noted that overall sports are becoming relatively MORE popular on TV in relation to other programming.

Still, another theory caught my eye:

For Mike Mulvihill, Fox Sports' senior vice president of programming and research, this summer reminds him of 2000, when the George Bush-Al Gore race was left undecided until December. That was the only year from 2000 to 2010 where all four NFL TV packages dropped from the previous year — Fox was down 4 percent, CBS down 10 percent, ABC down 7 percent and ESPN down 11 percent. It also was a year that saw World Series viewership drop by 22 percent. "I would really start with the election — I don't think you have to look much deeper than that," he said.

I can buy that, particularly since the first presidential debate went head-to-head with Monday Night Football (and I watched every minute of the debate and not a minute of MNF). The same thing will happen next week when the second debate is the same time as the Sunday night game.

But if the election is a factor, one would imagine it's a temporary influence. The other explanations, particularly digital migration, are far more permanent.

One factor not mentioned in the story as it pertains to the NFL: are enough fans conflicted by the long-term brain health of players that they watch less (or not at all)?

Whatever the case, with leagues so heavily dependent on TV revenue these days a drop in viewership is troubling. And a continuation of the trend would be alarming.