Two years back I estimated the point spreads in the four divisional NFL playoff games using a simple model of each team’s average margin or victory over the season based on these factors:
- net yardage from offensive and defensive plays;
- net sacks per game; and,
- net turnovers per game.
I have since added the effects of three other factors to my model for point spreads:
- net yards gained or lost during kickoff returns;
- net yards gained or lost during punt returns; and,
- net yards gained or lost due to penalities;
I have estimated the effects of these factors on each team’s average margin of victory using seasonal data for all 32 NFL teams between 2013 and 2016.
This table presents the results for the remaining eight teams in the playoffs. The top half of the table shows the net difference between the home and away teams on each of our six factors. For instance, Houston gained an average of 13.4 more yards per game compared to its opponents; for New England, the comparable figure is just 0.2. That gives New England a net deficit in yardage of 0.2 – 13.4, or -13.2 as reported below. The other figures in the top half of the table are similarly calculated.
Using my model, I can estimate the individual effects on the margin of victory (“point spread”) for each of these six factors. For instance, the effect for yardage is approximately 0.08 points per net yard gained, so the Texans’ 13.2 yard advantage on the ground compared to the Patriots is worth about 0.08 X 13.2, or 1.06 points, rounded to 1.0 in the table. The team with the greatest advantage in terms of yardage is Dallas, which gained on net almost 28 yards more per game against its opponents than did Green Bay. That difference is worth about 2.2 more points for the Cowboys in tomorrow’s game against the Packers.
When we add up the various effects of each of these six factors, Dallas has the greatest predicted advantage at slightly over three points compared to the Packers. Next comes New England, whose advantage stems largely from creating more sacks and turnovers than do the Texans. The Atlanta Falcons hold a slight advantage over the Seattle Seahawks, while the Kansas City Chiefs are predicted to lose to the Pittsburgh Steelers in their game Sunday night.
The last column on the right of the table shows the betting lines in Las Vegas for each game. These are comparable to my predicted point spreads. The 16 point spread for the Patriots over the Texans is outrageously high both by historical standards and by my estimates. Atlanta is also more favored by bettors than the teams’ 2016 performances would justify. And, despite my model’s prediction that Kansas City should lose to the Steelers in Arrowhead, bettors prefer the home team by a slight margin.