CHAMPAIGN, Ill. – Think your simple wagering strategy for professional football – such as always picking the home team or the underdog – is going to pay off in the long run? Don’t bet on it, say sports economists Scott Tainsky and Yoon Tae Sung.
Their analysis of National Football League game outcomes and betting strategies – such as picking the favorite, the underdog, the home team or the road team, or combinations of these factors – suggests that although these tactics may be successful over short periods of time such as a single season, the average bettor is unlikely to profit in the long run.
The sole exception may be betting on teams coming off a bye week – especially if the team is the favorite and is playing a road game.
Tainsky and Sung analyzed all regular season games from the NFL’s 2002-2009 seasons to explore the efficiency of the sports betting market and whether simple wagering strategies could beat the market over time. Specifically, the researchers wanted to examine whether odds makers and bettors were attuned to any potential advantage posed by teams that were returning to play after a bye week, or a week off from competition.
“Several psychology studies have shown that time off and vacations have positive effects on workers’ performance, so, theoretically, football teams could have an edge over their opponents after a bye week,” said Tainsky, a professor of recreation, sport and tourism in the College of Applied Health Sciences at the University of Illinois. “In the latest collective bargaining agreement, players are guaranteed at least five consecutive days off during their bye week, a clear recognition by management and players that teams benefit from rest. If the betting market is fair and efficient, the odds set by bookmakers and bettors’ probability of winning bets on these teams should reflect that.”
Across all eight seasons studied, bettors who used the simple strategy of picking the home team would have won only 48 percent of their bets, the researchers found. However, after teams’ bye weeks, bettors’ probability of winning improved considerably, especially if they bet on teams that were the favorites and were playing away games.
“Away favorites’ cover percentage was a little over 73 percent,” Tainsky said. “But when both teams were coming off a bye, the favorites won 59 percent of bets – and that jumped to 71 percent for away favorites.”
Although, theoretically, all teams should benefit from extended rest periods, better caliber teams seemed to benefit more, exceeding expectations after bye weeks. However, underdog teams playing at home covered the point spread during only 45 percent of their post-bye week games, despite indications by previous researchers that betting on home underdogs yielded positive returns.
Tainsky and Sung speculated that road teams’ performance may be enhanced by the collective experience of shared travel, conflicting with commonly held beliefs that teams have an unmitigated advantage when playing at home and are disadvantaged when on the road.
The researchers explored several possible explanations for the post-bye week pattern, in particular whether bookmakers’ forecasting and point spreads were in error, or that the effect might be limited to certain point spreads, but did not find any evidence to support that.
Since none of the other simple betting strategies would have enabled bettors to beat the market over the eight-year period studied, the researchers concluded that the NFL betting market appears to be efficient overall. However, bookmakers and bettors may be underestimating the benefits of bye weeks on teams’ performance, if the patterns found in the study persist in the current market.
“It would have been – and it may still be – possible for bettors to beat the market if they put their money on the away favorites coming off a bye,” Tainsky said. “But further investigation is needed to determine if this finding is specific to the league or to the sport.”
The study was published online Nov. 23 in advance of publication in the Journal of Sports Economics.
Sung, who earned his master’s degree at Illinois, is pursuing a doctorate at Florida State University.
