What's with these scoreless first quarters in primetime?

The Chicago Bears and Dallas Cowboys played a scoreless first quarter on Monday Night Football. If it seems like you've been seeing a lot of 0-0 games through the opening quarter of primetime games this year, it's because you have been.

Of the 13 night games played so far during the 2012 NFL season, seven have been scoreless after the first quarter. All three primetime games this week featured scoreless firsts. Last year, there were three total scoreless firsts in primetime games.

Even more remarkably, in 50 non-primetime games this season, only two have been scoreless after the first quarter.

That's a 0-0 first quarter in 54 percent of primetime games versus four percent of day games.

What's the reason? Perhaps there's some underlying cause that involves replacement refs and actual officials. Or it could be related to short weeks on Thursday and increased nerves in big Sunday and Monday games. More than likely, it's a completely random occurrence that will correct itself over the course of the season.