You might remember that a while back I toyed with building my own rankings system to rank professional and college sports teams. With a little free time recently, I went back to that and revised my rankings and I think I found something better. I used data from NFL seasons dating back to 1940, every college football season and some NHL data. I also created a few custom data sets to see how my system reacted to a few things. The results are here. As a teaser though, I thought I'd share the 15 most dominating teams in NFL history (based on this ranking). This ranking doesn't compare the teams to each other, but each against how much they dominated the rest of the league (i.e. #1 wasn't necessarily better than #2, but #1 dominated their league that year more than #2 dominated theirs). Without further adieu:

• 15. 1962 Green Bay Packers - This team's only loss that year was on the road to the 11-3 Detroit Lions, and the season ended with an NFL championship.
• 14. 1989 San Francisco 49ers - The 1989 49ers lost two regular season games, to the 11-5 Los Angeles Rams and the 10-6 Packers. The team later went on to beat the Denver Broncos 55-10 in Super Bowl XXIV.
• 13. 1982 Washington Redskins - In a strike-shortened season, the Redskins went 8-1 in the regular season, losing only to the Dallas Cowboys, who finished second in the conference. In the 16-team NFL playoff, the Redskins won four straight to win Super Bowl XVII.
• 12. 1978 Pittsburgh Steelers - The Steelers finished the regular season 14-2, losing only to the 12-4 Los Angeles Rams and the 10-6 Houston Oilers (both playoff teams). In the playoffs, the Steelers went on beat Dallas 35-31 in Super Bowl XII.
• 11. 2004 Pittsburgh Steelers - The Steelers finished the regular season 15-1, losing only to the Baltimore Ravens on the road in week 2. This team eventually lost in the AFC championship game to the New England Patriots, who make an appearance later in this list.
• 10. 1991 Washington Redskins - The Redskins only regular season losses were to the up-and-coming Dallas Cowboys and at the end of the season to the Philadelphia Eagles. The Redskins went on to beat the Buffalo Bills 37-24 in Super Bowl XXVI.
• 9. 1986 New York Giants - The Giants lost two regular season road games to the Dallas Cowboys and Seattle Seahawks. The team went on to beat the Denver Broncos 39-20 in Super Bowl XXI. This teams greatest accomplishment, however, was creating a small sports tradition of dousing the head coach in Gatorade after every victory.
• 8. 1984 San Francisco 49ers - The 49ers lost just one regular season game, to the playoff-bound Pittsburgh Steelers, and went on to beat the Miami Dolphins 38-16 in Super Bowl 19.
• 7. 1968 Baltimore Colts - The Colts only loss came to the Cleveland Browns, who they later trounced in the NFL championship game. The Colts later lost Super Bowl III to the New York Jets, but Baltimoreans will be quick to remind you that this was before the NFL-AFL merger, so the Super Bowl was just an exhibition game, and the Colts are the rightful 1968 NFL champions.
• 6. 2003 New England Patriots - The Patriots lost two early-season road games to the Buffalo Bills and Washington Redskins before winning 15 consecutive games (12 regular season and 3 playoff) culminating in a 32-29 Super Bowl XXXVIII victory over the Carolina Panthers.
• 5. 2004 New England Patriots - The Patriots again lost only two games, both on the road, and one to the Steelers who also appear on this list. In the process, the team extended their winning streak to 21 games before losing their first in week 7. The season concluded with a Super Bowl XXXIX win over the Philadelphia Eagles, 24-21.
• 4. 1976 Oakland Raiders - The Raiders lost just once, on the road, to the 11-3 New England Patriots. The team went on to run the table and win Super Bowl XI, 32-14, over the Minnesota Vikings.
• 3. 2007 New England Patriots - The Patriots finished the regular season 16-0 in games that often resembled early-season college games more than NFL games. The team went on to lose Super Bowl XLII to the New York Giants, 17-14, making them the biggest chokers in NFL history.
• 2. 1985 Chicago Bears - Much has been said of this team, and this ranking system obviously feels very highly about them. The Bears lost one game to the inspired Miami Dolphins before heading to the playoffs and winning by scores of 21-0 over the New York Giants, 24-0 over the Los Angeles Rams, and then 55-10 over the New England Patriots in Super Bowl XX.
• 1. 1972 Miami Dolphins - Perfection is hard to argue with and this team remains the only perfect season in NFL history. The Dolphins won all of their games in 1972, ending with a 14-7 victory over the Washington Redskins in Super Bowl VII. Much is often said to malign this team, with arguments that they didn't dominate their foes that way that other teams did. But based on the fact that the Dolphins went on to win the Super Bowl the following year, I'd argue that there was something to this team.
 
Of the 15 teams on this list, 13 went on win their championship (counting the 1968 Colts), one (2007 Patriots) lost in the Super Bowl, and one (2004 Steelers) lost in the AFC Championship game to another team on the list (2004 Patriots). With that in mind it should be said that this ranking system definitely favors teams that play in leagues with expanded playoffs, so its hard to compare teams across different eras. The playoff results cause good teams' ratings to get inflated, which is a good thing when you're trying to crown a champion, but bad for comparing across seasons. I tried to do a similar ranking for college football but the BCS era has pushed post-1992 ratings very high for the best teams. (1992 was the first year of the Bowl Alliance, which evolved into the Bowl Coalition which ultimately became the Bowl Championship Series).