|Issue # 1||Games through September 21, 2009|
Key Numbers in the NFL - Buying the Extra Half Point
The NFL regular season got underway last week with the usual number of surprises (i.e. upsets). 7 of the 16 games were won by the road team. After a 2005 season in which favorites covered 58% of the time, the pendulum swung the other way in 2006 with underdogs covering 57% of all games. In 2007 Favorites covered the spread 55% of the time. 2008 was a bookmaker's delight as Favorites and Underdogs were separated by just a single game from being exactly 50/50.
In 2009's first week Favorites went 8-8 ATS (Against the Spread). Of the54 teams favored by more than a TD, only Seattle was dominant, shutting out St.Louis 28-0. New Orleans did win and cover against Detroit and Baltimore barely covered -13 by defeating Kansas City 38-24 after the game was tied at 24. The other two heavy favorites both needed last minute rallies just to win straight up. Both occurred Monday night when New England (-13) rallied from an 11 point deficit to edge Buffalo 25-24 and a few hours later San Diego (-10) also came from behind to defeat Oakland 24-20. Thus ended an entertaining week that began last Thursday when Pittsburgh needed OT to edge Tennessee 13-10. The fun - and last minute heroics - has begun!
Although just 5 of the 16 games were decided by 4 points or less the pointspread came into play in 5 games and there were only 3 games decided by more than 17 points..
8 of 16 games went OVER the closing Total with 8 staying Under. An average of 40.6 total points per game were scored compared to an average Over/Under line of 42.6 as set by the linesmaker. Scoring was at its highest level in more than a quarter century in 2008 as teams combined to score 44.1 points per game.
As is the case each season, we do not want to overreact to the results of the first week of play. At the same time we don't want to fail to react. Many more questions were raised by these results than were answered - many more. Keep in mind the matchups that occurred. Remember that when two good teams meet, one good team must lose. And when two bad teams meet, one bad team has to win. By keeping results in context we can better put things in proper perspective as the season unfolds, week by week.
Over the years i often share insightful research with our readers that may help in the enjoyment, understanding of and profiting from the football experience. This week i will address the issue of key numbers - numbers that occur most often in terms of NFL victory margins. 'Key numbers' are often misunderstood. Let's take a look at what we mean.
The number '3' is the most common margin of victory. But do you know to what extent and how often it occurs? The answer is that over 15% of all NFL games since 1981 have been decided by exactly 3 points. That's over 1 game in 7. Put another way, at least two games each week can be expected to be decided by exactly 3 points. That is by far clearly the most common margin in the NFL -- almost double the next most common margin, 7 (just over 8% of all games).
It is a frequent discussion as to whether a bettor should 'buy' the extra half-point in games involving 'key' numbers. For instance, if you wish to play an underdog that is currently listed at + 3 ½ you have the ability to get + 4 on that team by laying 6-5 (12 to 10) instead of the normal 11-10. Buying that extra half point increases your break even point from 52.38% (at 11-10) to 54.56% (at 6-5). Likewise, if a favorite is - 6 ½ you could buy the extra half-point and lay only - 6.
Most people are aware of the importance of the number '3' and impulsively answer 'yes' when questioned as to whether they should 'buy down' when playing a favorite a half-point away from a key number and that they should 'buy up' when playing a similarly situated underdog. But is this the correct thing to do? Should you lay the extra 'vig' to buy that half point? Or are you giving away too much? Let's examine the issue.
The proper question is not how often does a final margin result in 3, 7, 6 or other key numbers. Rather, the proper question is how often does a 3 ½ point favorite win by exactly 3? Or, how often does a 2 ½ point underdog lose by exactly 3 points? Those two questions concern the changing of potential losses into pushes. But you can also ask how often does a 3 point favorite win by exactly 3 points (so that buying down to - 2 ½ changes a push into a win)? Or how often does that 4 point underdog lose by exactly 4 points (so that buying to + 4 ½ turns that push into a win).
First, here are the top 10 key numbers. These ten numbers combine for over 60% of final margins in NFL games over the past 287 seasons. The numbers are listed with their frequency of occurrence.
3 - 15.39% 10 - 6.04% 4 - 5.40% 1 - 4.21% 17 - 3.78% 7 - 8.12% 6 - 5.63% 14 - 4.71% 2 - 3.92% 11 - 3.32%
We've studied the past 6 and the past 27 seasons to see how often games within a half-point of a key number fall on that key number. Note that while over 15% of all games land on 3, some of the games are won by the Underdog and in most of the games the line was other than 2 ½, 3 or 3 ½. That's what we're trying to analyze. In the following chart the first number represents for results for the past 6 seasons (2003 through 2008) and the second number represents 27 seasons' results (1982 through 2008).
Critical # *
Pointspread Range # of Lines (A) # of Lands (B) * Pct. Of (B) / (A) ½, 1 or 1 ½ 93 / 486 Land on 1 1 / 6 1.08 % / 1.23 % 1 ½, 2 or 2 ½ 162 / 862 Land on 2 3 /25 1.85 % / 2.90 % 2 ½, 3 or 3 ½ 512 / 1851 Land on 3 44 /171 8.59 % / 9.24 % 3 ½, 4 or 4 ½ 261 / 1075 Land on 4 10 / 27 3.83 % / 2.51 % 5 ½, 6 or 6 ½ 207 / 834 Land on 6 7 / 22 3.38 % / 2.64 % 6 ½, 7 or 7 ½ 249 / 966 Land on 7 11 / 42 4.42 % / 4.35 % 9 ½, 10 or 10 ½ 103 / 413 Land on 10 8 / 25 7.77 % / 6.05 % 10 ½, 11 or 11 ½ 62 / 221 Land on 11 0 / 3 0.00 % / 1.36 % 13 ½, 14 or 14 ½ 31 / 152 Land on 14 0 / 4 0.00 % / 2.63 % 16 ½, 17 or 17 ½ 6 / 33 Land on 17 0 / 2 0.00 % / 6.06 %
Critical # *
* Only the # of times when the FAVORITE wins by the specific marginAs you can see, with the exception of the key numbers '3', '7' and '10' the percentage of times the 'key pointspread' and the 'key result' coincide is quite small, 4 percent or less. For example, of the 834 times a team was favored by 5 ½, 6 or 6 ½ points between 1982 and 2008 that favored team won by exactly 6 points just 22 times, or 2.64% of the time. What does this mean? We'll have a follow-up discussion next week.