Anatomy of a Pointspread

The pointspread is not the handicapper’s predicted margin-of-victory, but it is in fact the handicapper’s opinion of what number will be required to split the wagering evenly on both teams. Now I will discuss in a little more detail how the pointspreads are derived and what you need to know to take advantage of the numbers.

Linemakers are divided into two groups, oddsmakers and bookmakers. Oddsmakers deal in a theoretical world because they don’t actually take bets on the lines that they publish. Oddsmakers make their money by selling their lines to media outlets, sportsbooks, etc. These are the lines you see in your local newspaper or hear on the radio. The lines don’t change very much from day to day, because there are no direct wagers placed on these lines, and as such, there are no line moves required to try and balance action. On the other hand, bookmakers deal very much in the real world, as they take bets on the lines they publish. These lines then move as a result of wagering, because the books seek to balance action in an effort to minimize risk and maximize the vig (commission) collected. This fundamental difference is one of the main reasons that the lines you see in your newspaper are not the same lines you get when you deal with a sportsbook. It is worth mentioning that time is also a factor. The lines in your paper were probably accurate when they were submitted to the editor, but in the amount of time that passes from pre-production to when you read the paper, injuries, weather and other factors can dramatically shift the spread.

Linemakers use a variety of methods to calculate their idea of the pointspread. I cannot say which methods are best, or who is the most accurate. If I had this figured out, I would be sitting on a beach somewhere, sipping piña coladas and enjoying my millions won betting on sports. Some use complicated computer programs that factor in recent performance, injuries, player match-ups, etc. Others simply have a feel for the games and produce a number out of thin air (I’ve met a couple of guys like this who look at next week’s schedule and say “they’ll be a 5 point favorite” and sure enough the line will open at 4.5!). However, most line makers use power ratings or some derivation. Power ratings involve assigning each team a numerical value based on performance and than comparing the ratings to generate a pointspread. For example, one set of ratings I saw this week had Miami rated 57 at home and Indianapolis rated 53 on the road, so the difference results in a 4 point line. Another set has Miami rated 77, Indianapolis rated 75, and gave a 3.5 point advantage to the home team so it predicted an opening line of 5. The actual line opened at 6 at some books, and was bet down quickly to 4.5, so it appears that 6 was too high. There are no standards for how to derive these ratings, and predicting actual outcomes with better accuracy than the majority of the betting public is your key to success.

Some sportsbooks base all their lines on their own internal linemaking, but the majority of books rely either solely on oddsmaking services or a combination of external service and their own handicapping. I asked Kent, BoDog’s top bookmaker, how he derives lines, and he explained that his team handicaps the games themselves, compares these results to the opening lines out of Vegas and then adjusts for the historical action of its own player base before coming up with a consensus opening number for each game. From there, the numbers are moved only to balance action or to account for special circumstances such as weather, injuries or the like. (I’ll discuss balancing action and the risks some books take in an upcoming issue.) After finishing his research, Kent opened his Miami line at 4.5, and didn’t have to move much at all.

Now that we know how lines are generated and where sportsbooks get them from, lets discuss what you need to do to win. You have some advantages over the sportsbooks that can compensate for the vig you pay on a winning bet. The key advantage is that you do not have to wager on every game, you can pick and choose your wagering opportunities. The bookmaker puts up a number on hundreds of events each and every week. In a typical NFL week, there are 14 to 15 games for you to choose from and there are even multiple betting opportunities on each game. You may not have a good feel for every game, but you most likely see several games where you are confident that one team will cover with better than 53% probability (you need to be better than 52.4% to cover the vig, we’ll discuss this more in another issue). This is what handicappers refer to as an “overlay” or “getting value”. For example, if you think Miami will win by 10 points and the pointspread is only 4.5, you have an overlay. The odds appear to be in your favor and if you find enough of these situations, you can make a profit betting on sports.

Next week, I’ll cover in even greater detail the best way to take advantage of overlay situations when I discuss “beating the number”.