HFA in the Playoffs Historically
Home field advantage (HFA) has always played a major part in the NFL – in fact, between 1981–96, home teams racked up an impressive 58% win rate. Sports psychology literature has attributed this phenomenon to various factors, including:
• Learning factors (e.g., familiarity with the stadium and its playing surface)
• Travel factors (e.g., visiting teams experience physical and mental fatigue and disruption of routine)
• Crowd factors (e.g., crowds may provide social support)
• Referee bias in favour of the home team
• Team members who expect success perform better in the presence of an evaluating audience (e.g. a home crowd), whereas those who expect failure perform worse.
• Inflated testosterone levels in home players (defending territory)
In fact, HFA advantage reoccurs across amateur and professional baseball, football, basketball, and ice hockey, with Prof. Barry Schlenker of Florida University calculating that in several studies, home teams have been found to win more often than visiting teams from 53% to 64% of the time.
When the bookmaker’s handicap (or spread) was taken into account, however, the home teams over the same period produced a win rate of 49.9%, indicating that the traders were almost perfect in their odds predictions. For standard games, Home Field Advantage had no effect on spreads.
This wasn’t true for playoff and Monday Night football games, however. At these high-profile events, the win rate after the spread was 59.2% for the home side. And for home team underdogs, the win rate against the spread (ATS) increased to an incredible 65.5%. But do these behaviours still hold true today?
NFL Playoff Betting Spreads – HFA No More
During the six seasons since 2007, home sides have won 37 of the 60 post-season games in the run-up to the Super Bowl – an impressive 61.7%. However, the home side covered the spread in just 29 of those 60 games – just 48.8%.
In fact, over the last six seasons the average spread for home sides, -3.86- is almost identical to the average of the actual win margin of the matches – 3.83. The difference of just -0.03 between the handicaps and the actual result is almost insignificant.
Therefore any advantage that HFA spread betting in the playoffs had has been annulled by informed bookmakers and sharp bettors shaping the odds.
Bet Early to Maximise HFA Impact
If we consider opening lines instead of closing lines, however, we can see just how much bookmakers are compensating for the perceived Home Field Advantage.
The average spread for the opening lines over the last six seasons is -3.69, which is lower than the average win margin by 0.14. This means the spreads are over four times less accurate when they open than after the market has optimised them.
This can in part be explained by square money pouring onto favoured home sides, which tends to accelerate the closer you get to the start of games.
It’s important, therefore, to realise that while bookmakers have adapted to compensate for HFA, lessening any advantage for bettors over the lifetime of a market, traders still require smart bettors to sharpen their odds. And therefore when betting on NFL playoffs – like other markets – it’s best to bet early.