Fantasy Football Definition of Bye Week
A "bye week" is a week that an NFL team has off. The NFL Season has 17 weeks and 16 games per team, so each NFL team has one bye week per year. While NFL players look at their bye week as a blessing, because they can rest and heal from injuries, fantasy football owners dread bye weeks, because key starters will be out of their lineup. When drafting in a fantasy football draft, teams often draft to avoid repetitive bye weeks at certain position. For instance, if you draft two quarterbacks and your starting QB has a Week 7 bye, then you will draft your backup quarterback from among the remaining QBs that don't have a Week 7 bye week.
NFL Bye Weeks
The National Football League did not permanently institute bye weeks until 1990. Before that, every team had a 16 week season fit into a 16 week schedule. The NFL decided the bye week would extend the NFL regular season television schedule by one week, while also giving their players a week of rest during the season. While there have been a few changes in the bye schedules since 1990 (two byes in 1993, more byes in certain weeks in other years), this has remained the basic bye week format since for two decades.
NFL Bye Week Schedule
Bye weeks begin in Week 4 and end in Week 10, which runs in the middle half of the fantasy football regular season. From weeks 1 through 3 and weeks 11 through 13, also usually regular season weeks in fantasy football schedules, teams have the full use of their rosters. Some 12-team fantasy football leagues with 3 divisions of 4 teams will schedule their divisional match-ups in Weeks 1-3, then rematches of those match-ups in Weeks 11-13, giving teams their full roster when playing their divisional rivals.
NFL teams prefer to have their bye week later in the season, because they have fewer injuries and less fatigue by the time the earlier bye weeks come around. In fact, certain players and coaches have complained about the league assigning them early byes, when their rivals get later bye weeks. The idea is that a team with a Week 10 bye is able to get a week of rest virtually in the middle of the season, allowing them to prepare better for the final stretch of the NFL regular season. Those with a Week 4 bye week must play the last 13 NFL weeks without a week of rest.
Fantasy Football Bye Weeks
Most fantasy football teams end up with one or two weeks that are more heavily affected by their players byes. For instance, if you have one or two key running backs out on bye the same week, your team will be severely undermanned in that week. If you have two or more star wide receivers off the same week, this can weaken your receiving corps for one key week of the fantasy season. Compounding the trouble caused by bye weeks are injuries. If you have a key injury or two and then have key bye weeks happen at the same time, even a strong fantasy football team can become an underdog for that week.
Often, one fantasy football team will draw a schedule where several of their opponents just so happen to have their 1st and 2nd round draft picks on byes. This creates a situation where one team in your fantasy football league can luck into an easier schedule than their opponents, and this kind of bye week break can sometimes propel an inferior team to a superior record and their division title. If you want to get a general idea of whether you have caught a break on bye weeks in your fantasy schedule, go through your opponents' rosters and count up how many players those teams have that are on bye weeks. If you have more opponents' players on bye weeks than are on your roster, you're ahead of the average and caught a break.
This can be deceptive, though. For one, teams are likely to make free agent moves and trades, so you won't know how the situation looks until the week of your match-ups. Two, an opponent might have four players on a bye week, but those players might all have been bench players, anyway. A team missing one or two key starters is much more affected.