Sweeps are not exactly uncommon in the series between the Cowboys and Redskins. Dallas managed to sweep Washington in both 2011 and 2013, so it has not been that long.
It just seems, however, that when one team is having an especially great season, the other will come along and wreak havoc.
Washington lost one game in a strike-shortened 1982 season and eventually won Super Bowl XVII. The team to beat the Redskins?