The 2012 NFL Divisional Round playoff games are this weekend. The four teams hosting games rested and recovered last week while the lower-seeded opponents played their 17th game of the season.
The NFL expanded the playoffs to 12 teams for the 1990 season, giving the top two seeded teams from each conference a bye week. These are coveted seeds; you won’t find a single team that would prefer to play in the Wild Card round to taking a week off.
The primary reason for this is the length of the NFL season and the toll it takes on the athletes’ bodies. An extra week allows injuries more time to heal and every NFL player is injured in some form or another by the end of the regular season.
Even when healthy, the extra week gives all of the athletes what sports physiologists refer to as recovery time.
Most athletes know that getting enough rest after exercise is essential to high-level performance, but many still over train and feel guilty when they take a day off. The body repairs and strengthens itself in the time between workouts, and continuous training can actually weaken the strongest athletes.
Rest days are critical to sports performance for a variety of reasons. Some are physiological and some are psychological. Rest is physically necessary so that the muscles can repair, rebuild and strengthen. For recreational athletes, building in rest days can help maintain a better balance between home, work and fitness goals.
The bye-week teams are also playing at home. Home-field advantage is no myth, and the effect is modulated by the stadium and climate. NFL teams won 57 percent of their regular season home games over the last 10 years.
All else being equal, we should expect that home teams have an advantage in the playoffs. But is there an additional competitive advantage for bye week teams?
Recovery v. Momentum
After the Indianapolis Colts secured a playoff spot in week 16, I suggested that the Colts now had an opportunity to rest some key players and their walking wounded in week 17 versus the Houston Texans.
B/R readers universally disagreed, arguing that there was more benefit to playing the game (for more practice) and beating the Texans (to motivate the team). Most of the counterarguments to the Colts resting players centered on the nebulous concept of momentum, that sports teams need to keep playing at regular intervals to maintain the teams’ confidence and rhythm.
Last week I demonstrated that the “hot team” argument for playoff success is essentially a myth. NFL fans can recall examples of “hot” teams, but there is no evidence that a team’s end-of-season performance affects that team’s playoff performance.
Last weekend’s Wild Card round demonstrated this point. The Colts entered their playoff game with the Baltimore Ravens on a two-game end-of-season win streak, including a thrashing of the Texans. The Ravens were the epitome of a “cold” team, losing four of their last five regular season games. The Ravens won 24-9.
Which is more important for playoff success?
This outcome is an example of the benefits of rest versus the myth of momentum. The Ravens rested six starters the last week of the regular season, a 17-23 loss to the Cincinnati Bengals while the Colts played for keeps against the Texans.
The Texans, who lost three of their last four, beat a Bengals team that was on a three game end-of-season win streak. Similarly, the Green Bay Packers lost to the Minnesota Vikings in the last game of the regular season then turned around and beat them in the first round of the playoffs. The Vikings had a four game end-of-season win streak.
The Redskins, however, played the last week of the regular season in a must-win game against long-time bitter rivals the Dallas Cowboys. The Seahawks, meanwhile, beat a mediocre St. Louis Rams. The Redskins couldn’t rest star rookie quarterback Robert Griffin III against the Cowboys and he limped off the field late in the game against the Seahawks.
These examples are anecdotal evidence that rest and recovery at the end of a long NFL season are more important than momentum. The statistical evidence demonstrates the myth of momentum in the playoffs. Is there similar evidence that rest and recovery impacts success in the NFL playoffs?
Bye-week teams will have a high winning percentage in Divisional round playoff games because of home-field advantage. But if bye-week teams have a higher winning percentage than other home-field NFL playoff teams, at least some of that difference could be due to rest and recovery.
Using playoff data from 1990-2011 I calculated the winning percentages for home teams in each round of the playoffs. In the table below bye-week teams have a higher winning percentage in the divisional round than home playoff teams in the Wild Card round and the Conference championships.
All Playoff Games
Home Team Win Pct.
Home-field advantage is more pronounced in the NFL playoffs than in the regular season. Home teams in the playoffs win 68 percent of the time compared with 57 percent in the regular season. Some of this may be due to the rigors of travel at the end of a long season or it could simply be that the better NFL teams have higher home-winning percentages to begin with.
When the comparison is limited to only NFL playoff teams we can see the benefits of the bye-week to teams with similar ability. The bye-week team wins their Divisional round game 74% of the time.
In the two playoff rounds that bookend the Divisional round, the home-winning percentage is nearly 10 points lower. This means that teams who have rested and recovered during the Wild Card round win more games than other home playoff teams. Interestingly, the effect completely disappears by the Conference championship round.
Similarly, there is no bye-week effect in the Super Bowl. Seven non-bye-week teams have won the Super Bowl and every one of those teams beat a bye-week team. Four non-bye-week teams have lost a Super Bowl so the record for non-bye-week teams in the Super Bowl is 7-4, not too shabby.
Rest and recovery seems to have the greatest effect when a rested and recovered team plays a team that had a difficult game the week before. When both teams played the week before there is no advantage. This is compelling evidence that rest and recovery does have a positive effect on NFL performance.