The 2018 NFL shedule has an odd quirk in it this weekend, as the Miami Dolphins, New England Patriots, Buffalo Bills, and New York Jets all head into their bye week. Going back through all of the schedules each year, the last time one division had all of the teams on a bye week was in Week 8 of 1998, when the NFC East had the Dallas Cowboys, New York Giants, Philadelphia Eagles, Washington Redskins, and Arizona Cardinals all off on the same weekend. Week 5 of that same season also saw the AFC Central - Jacksonville Jaguars, Tennessee Titans, Pittsburgh Steelers, Baltimore Ravens, and Cincinnati Bengals - all have their bye (along with the St. Louis Rams of the NFC West).
That year also saw the Dolphins, Patriots, Bills, and Jets all have their bye in Week 4, but the Indianapolis Colts were in the AFC East at the time and did not have an off weekend until Week 8 - along with the entire NFC East.
Prior to 1998, it was not unheard of for an entire division to be on the bye, or four of the five teams of at a time, with the fifth sliding into another weekend. In 1997, the AFC West, with the Denver Broncos, Kansas City Chiefs, Oakland Raiders, San Diego Chargers, and Seattle Seahawks were all off in Week 7. The AFC East again saw four teams, Miami, New England, Indianapolis, and Buffalo, off in Week 5, while the Jets waited until Week 9 for their bye week.
Basically, it is not something completely new to the NFL, but it is not something we have seen in 20 years, and not something that has happened since the realignment into four divisions per conference. It is an odd quirk of the schedule this year, and one that seems odd as we reach the games for Week 11.