NFL odds are based not only on power ratings but on public perception. There is much more, however, than just the reputation of the two teams involved in a game that ultimately makes up the football odds. NFL are set based on what the public is likely to bet.
NFL will have the marquee teams favored most of the time. For example, the New England Patriots from 2001-2004 were one of the most profitable teams on the NFL odds board, beating the spread at well over a sixty-percent clip in that time span. Then add to the fact that they had won three Super Bowl championships in those four seasons, including back-to-back in 2003-2004 and you have a team that the mainstream gambling public had at the very top of their list.
The NFL odds makers, knowing how the public perceived New England, over-charged gamblers who wanted to take the Patriots at the start of 2005, and as a result of this the Patriots won just four of their first eleven games against the football odds. The last few games of the season the Patriots bounced back versus the NFL, but that was only after crushing their followers early in the season.
That example shows exactly what happens with NFL all the time. The NFL odds makers will start to overcharge gamblers for popular teams. In that previous example the NFL odds makers lowered the price on the Patriots after the public finally got off them. This type of reaction in NFL happens with teams like New England, Indianapolis, Dallas, Pittsburgh and others.
What does all this tell you about perception in NFL ? It says that the public perception of a team is a good thing to go against in football odds. Once you are on the bandwagon with everyone else you better realize it is time to get off. Once public perception is with a team in football odds you better realize that team has lost value and is no longer a good bet. Conversely, when the public gets off a team you might want to seriously consider taking them in their next game. It is all about perception.