The Los Angeles Chargers' season is considered effectively lost less than two months into the campaign.
That collapse is striking because, before the season began, they were seen as one of the AFC's five or six leading contenders.
The NFL has completed about one-third of its season, with the halfway point nearing.
Unexpected results have emerged, and some teams' playoff hopes are already over.
Of the league's 32 teams, half have no immediate cause for concern, though that may not last.
The other 16 need to turn their seasons around quickly.
Teams under pressure are grouped into tiers reflecting how worried or panicked they should be at this point.