For fun, we looked back at the the actual outcomes of every game of the 2010 through 2014 NFL seasons. The output of this examination is shown above in the form of a histogram. A couple of interesting, and hopefully, instructive observations flow from this review:
1. Be wary of spreads of 3's, 7's and combinations thereof...
The most typical outcome in the NFL over the last five years has been the home team losing by three points (of our 1,334 game sample, this result was realized in 97 instances, or 7.27% of the time). The second most common result was the home team winning by 3 (91 occurrences).
Beyond 3, the next most frequently recurring margins were +7 and -7. These results were realized almost equally (60 and 57 times, respectively) and collectively account for about 9.0% of the games in our dataset.
-6 was also quite common, as the home team won by this margin in 52 instances, or 3.9% of the time. This makes intuitive sense: if a 3 point score differential, which represents the points value of a field goal, is common, it does not appear a stretch to imagine that home team victories by two field goals are likewise reasonably typical. Less intuitively though, during the period under review, home teams lost by two field goals with much less regularity -- on a mere 26 occasions of 1,334 total games.
2. Fear not the double digit line...
Over the sample period, home teams won by a double digit margin in more than 30% of all games played. Conversely, the home team lost by 10 or more in better than 19% of games played. Thus, in almost half of the contests we looked at, games were decided by 10 points or more.
As such, though conventional wisdom holds it better to fade the favorite when the spread is large, we recommend that bettors not shy away from the big chalk when a reasonable basis exists for a bet -- especially when home team is the play.
Happy betting!!