32. Los Angeles Chargers (Average Attendance: 33,796)
As mentioned in the intro, the Chargers play at the StubHub Center which is the home of the LA Galaxy soccer club. The StubHub Center has half of the capacity of normal football stadiums, which makes it impossible for them to compete with other NFL franchises in regard to attendance until their new stadium is built.
The underlying problem in their attendance is that most of their fan base was alienated when the Chargers decided to move from San Diego to Los Angeles. The Chargers are having a great season, in which they are one of four teams that have won double-digits games this year. Yet despite having a great season, no one seems to care.