• The Giants celebrate their sweep over the Tigers.

If you just looked up and realized that the World Series is already over, you're not alone.

The San Francisco Giants' four-game sweep of the Detroit Tigers averaged an 8.9 overnight rating per game, putting the Series on track to become the lowest-rated ever, according to USA Today's Michael Hiestand.

Hiestand reported on Monday that the Series' first two games from San Francisco averaged just 7.7. percent of U.S. households, the lowest ratings ever for the first two games of a Series.

San Francisco is the sixth biggest media market in the country, and Detroit the 11th. And ratings were huge in those two cities.

So what gives?