Vegas lines are crucial in fantasy football because they give us a top-down look at how a game is most likely to play out. In providing a spread and over/under total, Vegas is essentially projecting a final score for each game, which can be used when making fantasy football lineup decisions. (To arrive at a projected team total, simply subtract the spread from the over/under and divide by two. This is the underdog's point total. To get the favorite's, add back the spread to the underdog's total.Note: Calculated implied totals can be found on the right hand side of each site's Lineup Generator.)
For quarterbacks, you are looking to target high over/unders and projected team totals. League-wide, roughly two-thirds of offensive touchdowns are scored via the pass.
For running backs, you are looking to target favorites -- the larger the spread, the better. NFL teams tend to run more frequently when they're favorites, which is due to the increased liklihood of being in positive game script that being the favorite entails. Furthermore, favorites have historically scored over 33 percent more rushing touchdowns per game than underdogs.
For wide receivers, the Vegas lines aren't as correlated with fantasy production as other positions, and you can sometimes get an edge in tournaments by playing wideouts on teams with medicore totals who will usually have lower ownership than most of the wide receivers on teams with high implied point totals.
For tight ends, like running backs, you should be looking for favorable Vegas odds: high spreads and team totals. The fact that tight ends, like running backs, score most of their touchdowns in close, and the fact that tight ends often run shorter, more conservative routes than wide receivers means that tight ends also benefit from positive game script.
For defenses, you are looking to target favorites in games where the defense's opponent has a low projected team total. You want a defense that is able to limit the opposing offense's point total so you can pick up points allowed bonuses. In addition, holding a lead benefits a fantasy defense because when an offense is forced to pass to catch up, there are more opportunities for the opposing defense to get valuable sacks and interceptions.
For kickers, you are looking to target favorites with high projected team totals. Being the favorite is important for a fantasy kicker, because there's less of a chance that a kicker's team will fall victim to negative game script, where the team has to go for touchdowns instead of field goals. A high projected team total is important for a fantasy kicker because he needs to be on a team whose offense will be able to consistently drive into field goal range and provide him with scoring opportunities.
The below app can also be used to view public betting trends, which are the percentage figures. ML = money line, Total = over/under S&T = spread and total.
*TO VIEW THE OVER/UNDER: click on "Side", choose "S&T" and then click "Go".