Inefficiencies in the football betting market

Is there an opportunity to systematically win in the NFL betting market?
If there is, possible sources of this opportunity, "market inefficiency", or "pricing error" may include:
Aggregate bettor biasObservable effects of the game being fixedOver compensation of the above by professional bettorsOf course, this analysis isn't going to do itself, so I needed to step up to the plate. I found some research on the topic, mostly focusing on simple betting strategies and all of them severely limited in timeframe (citations at link below). My analysis includes all regular season game data from 1978 to 2009. So let's get to the fun part!
Bet on the visitor3603 wins203 ties3600 lossesAnd then the obvious:
Bet on the underdog3735 wins203 ties3468 lossesOk... what about betting on a team when that team just lost to the opponent it is about to play within the past 21 days?
Payback in 21 days (after losing previous game)30 wins1 ties30 lossesPayback in 21 days (after losing …
If there is, possible sources of this opportunity, "market inefficiency", or "pricing error" may include:
Aggregate bettor biasObservable effects of the game being fixedOver compensation of the above by professional bettorsOf course, this analysis isn't going to do itself, so I needed to step up to the plate. I found some research on the topic, mostly focusing on simple betting strategies and all of them severely limited in timeframe (citations at link below). My analysis includes all regular season game data from 1978 to 2009. So let's get to the fun part!
Bet on the visitor3603 wins203 ties3600 lossesAnd then the obvious:
Bet on the underdog3735 wins203 ties3468 lossesOk... what about betting on a team when that team just lost to the opponent it is about to play within the past 21 days?
Payback in 21 days (after losing previous game)30 wins1 ties30 lossesPayback in 21 days (after losing …