Late Sunday afternoon and into the early evening is prime time for professional gamblers during football season. The sharps spend surprisingly little time watching the games they have bet on, preferring instead to dissect the early lines for the following week’s games, and crunch numbers seeking one or two mistakes which they can pounce on. Every so often during NFL season, oddsmakers – who are in a hurry to get lines on the board as soon as possible – trip up, and the pros want to be there when they do. And pros keep a close eye on the often-overlooked total, which many contend is easier to beat than the standard betting line.

Recreational bettors for the most part pay little attention to the O/U, and more than a few handicappers say that that is a mistake because with some work, betting over or under the total number of points scored in a given game can be easier than picking an ATS winner. The caveat is the word work. It doesn’t come free.

One thing that many handicappers also agree on is that bettors consistently undervalue the Under. Recreational bettors prefer offense to defense, but sharps look for opportunities to bet against the Over – and there are plenty of chances:

• Weather is a huge factor. Oddsmakers’ total number is based on a game being played in decent weather, and storms can hit the south early in the season and the north late in the year. If the number on this season’s Jan. 2 New England at New York Giants game is set the previous Sunday at 41.5 and early in the week a storm is predicted to move into the East, a hard Under play makes sense. If the storm hits you most likely will cash; if it doesn’t, you can still catch the Under if only one of the teams has an off day offensively. In 2008 a windstorm hit Buffalo on Dec. 28, and the Patriots passed only 6 times the entire game on the way to a 13-0 win that easily came in below the posted total of 35. Unders are almost always worth consideration in games played in the North (Buffalo, Pittsburgh, New England, New York, Green Bay, Chicago) late in the year. The number will never drop more than a couple of points, although some offshore books are compensating by keeping numbers stiff and adjusting the juice one way or another.
• Keep an eye on high-scoring teams and bloated numbers. With two high-scoring teams in last season’s Super Bowl, Vegas got big play early  on the Over, even with a 56.5 total (some sportsbooks dropped the number to 55 later in the week due to heavy betting on the Under). But adjustments were made defensively, not all bettors realized that to go Over both teams had to play well offensively, and the Under easily paid off when New Orleans won, 31-17. In big games some coaches tend to get conservative, depressing the total.
• Early in the decade 37 was the average number of points scored in an NFL game, but rules designed to help offenses have pushed that number up to 41.5. The half-point is crucial to O/U players because games can end 21-20, 24-17, 27-14. For lower-scoring teams (Cleveland, Buffalo, Tampa Bay), the number to look at is 37. Anything above that deserves a close look at an Under play; anything below should give the Over some consideration.

Seems easy. Just hit on 55 percent of your NFL bets and you can make money for the season. No sweat. Read up a little bit, check the Friday injury reports and let nature take its course. If an octopus can pick World Cup games correctly, how hard can it be to pick pro football winners?

But if it was that easy, lots of people would be making a living at it and sports books would be forced out of business in less than a month. Picking pro football games against the spread is part knowledge, part insight, part crap luck. Lots of factors play into it.

There are few secrets in the NFL, and that’s the way the league likes it. Injuries have to be reported, the Internet allows oddsmakers (and bettors) to mine franchises for information. All that results in tight lines that are hard to beat. But there are a few factors that bettors can look at before throwing down their money:

1. BET EARLY. Sportsbooks all try to be the first up with numbers, and the Vegas books and offshores are all trying to get early action. Games for the following week are often posted late Sunday afternoon. Be ready to hit as soon as you find a game that you really line. Make sure your team has not suffered any major injuries. Oddsmakers are good but not perfect; every once in a while they post a line that’s a few points out of whack. If/when they do, jump on it early before betting smooths out the number. Numbers rarely fluctuate more than a few points from late Sunday to game time the following Sunday, but you want those points in your pocket.
2. LIMIT YOUR BETS TO A FEW TEAMS. Knowledge is power, and it’s impossible to know everything about every game. Concentrate on fewer games and hit them harder. For several years I made an annual trip to Vegas and bet on every NFL game on a particular Sunday. The best I ever did was 8-6; the worst was 6-9. For the last few years I’ve limited myself to 3 games each Sunday and bet more, with better results.
3. RUN AWAY FROM DOUBLE-DIGIT FAVORITES (especially on the road). The public loves favorites, and dominant teams draw lots of play. But there is talent on every team, and the margin between winning and losing so narrow, that it makes no sense to give away huge numbers. In 2007 the Patriots went undefeated in the regular season and started 8-0 ATS. But in their final 11 games (including post-season) they were double-digit favorites 10 times, and were 2-9 ATS in those games. Flip the coin over and look at the 2008 Detroit Lions, who were winless (0-16) SU. After going 0-4 ATS to start the year, they covered three of the next four, with all three covers coming on double-digit lines. Detroit, in fact, was 7-1 that season when getting 10 or more points, and 6-0 on the road.