Forget what you think you know about home-field advantage when it comes to NFL betting

Sep 20, 2018 |

Home field advantage is ubiquitous throughout sports. There’s some debate over what causes it: do players play better? Do refs favor home teams? But there’s no doubt that NFL teams win more games at home than on the road. 

In football the conventional wisdom (and public opinion – the biggest factor for oddsmakers) says home field is worth about three points, but how does that stack up to the numbers?

Is home-field advantage shrinking?

From 2002-2009, sportsbooks were giving home teams an average of 2.5 points per game. From 2010-2017 that dropped to 2.3, suggesting perhaps home-field advantage is on the decline. Scoring numbers don’t seem to support that, home teams averaged about 2.55 points per game more than their opponents in both periods. However, those points aren’t translating to better results against the spread. Since 2010, despite covering the spread by a quarter of a point per game, home teams are 985-1,011-52 (49.4%) against the spread. 


Where home field matters most

This depends who you ask. Looking at oddsmakers’ differences, Arrowhead Stadium in Kansas City comes in as the biggest difference maker with the line moving 5.9 points for the Chiefs at home versus on the road - implying just under a 3-point home-field advantage (HFA). Other teams that come in near the top are a mixed bag: Houston, Seattle, Tampa Bay and Cleveland with HFAs between 2.7 and 2.9 points. No one’s surprised to see the Seahawks there. The others, however, probably weren’t near the top of your list.

If we instead look at game scores since 2010, Green Bay scores five more points per game and allows five points less per game playing at Lambeau Field - by far the biggest home-field edge. The Jets, Cardinals, Bills and Ravens round out the Top 5 with roughly 3.5-point swings for playing at home versus on the road. The Chiefs come in near the middle of the pack with a 2-point HFA.

Jerry’s World?

Where do bettors not expect home field to matter much? The Steelers come in at the bottom with less than a 1.5-point HFA. The Cowboys (stay tuned), Jets, Redskins and Rams are the only other teams below 2.

Performance wise, no one comes close to Dallas. Since 2010 the Cowboys have performed almost a half a point per game worse at home than on the road, blowing away the competition. In that same period, they’ve put up an impressive 36-29 away record (36-27-2 ATS) while playing below .500 straight up at home and going a woeful 24-42-1 (37.3%) ATS. Tampa Bay comes in as the second-worst home/away spread at 1.3ppg, which is interesting given Vegas lines imply a 2.5 point HFA.


Games I have my eyes on

Tampa Bay is only giving up one point as of this writing to the struggling Steelers. Tampa Bay comes in near the top of the Vegas home-field edge list and near the bottom of the observed HFA, making for an attractive fade. The Ryan Fitzpatrick show can’t last forever, and I like the Steelers to finally right the ship this week.

Kansas City has moved to a 6.5-point favorite against the 49ers after opening at -5. As mentioned K.C. has the biggest HFA based on betting lines, but has not performed up to expectations, with an observed HFA of just two points per game since 2010. Add in another quarterback – the young Pat Mahomes - who is unlikely to keep up his MVP-caliber pace and we have an interesting spot.

Seattle opened as a 3-point favorite against Dallas. Using the standard HFA edge, you’d think Vegas rates these teams equally, but this line implies a small edge for Seattle. That hardly seems warranted after Seattle’s embarrassing outing against Chicago - a team that has many similarities to the Cowboys. The line has dropped to Seattle -1.5, but I’ll be watching closely to see if it moves back up.

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