After writing a piece about whether or not the 2000 Ravens defense was the greatest of all time, it seemed like a natural follow-up to write about the greatest teams of all time. It also seemed like a natural to continue to use standard deviation as the "divining rod" of greatness. (If you need a refresher, check out an earlier column on the Ravens' defense.)

	Greatest teams countdown
	Date	Team
	4/30	1955 Browns
	5/1	1958 Colts
	5/2	1962 Packers
	5/3	1971 Cowboys
	5/4	1972 Dolphins
	5/7	1979 Steelers
	5/8	1989 49ers
	5/9	1991 Redskins
	5/10	1994 49ers
	5/11	1996 Packers
	5/14	1999 Rams
	5/15	1985 Bears

I decided to stick to one season instead of multiple seasons like Rob Neyer and I did in "Baseball Dynasties." (You didn't think I would leave out a plug for the book, did you?) Given that, I only considered teams that won the Super Bowl or NFL title in the pre-Super Bowl days. I started at 1950 because that was the year free substitution was made permanent, forever changing the way that pro football was played. I think it's very difficult to compare teams from the time when players played offense and defense to teams with separate offense and defense platoons. In order to give some meaning to the regular season, no wild-card teams were considered.

Last, but certainly not least, a performance measure based on standard deviations was used to separate the teams. I don't want this to turn into a math class, so I'll try to keep it simple. I developed a number which I call "Power Index" based on the number of standard deviations a team was from the league average in points scored, points allowed, yards gained and yards allowed.

I simply add those four components together, make an adjustment for strength of schedule, and voila, out comes the Power Index. For those of you familiar with "Baseball Dynasties," this is the same concept as the "SD Score," and the scale for Power Index is twice as large as the scale for SD Score. That is, whereas a +3.00 SD Score or higher was the mark of greatness for baseball teams, a mark of +6.00 or higher is the mark of greatness for football teams.

This makes sense as four categories are used for the Power Index while two were used for the SD Score. Since 1950, 20 teams have had a Power Index of +6.00 or higher after adjusting for schedule. How many do you think won the Super Bowl or NFL title (pre-1966)? The answer is 13, which ain't bad. Teams with a Power Index of +6.00 or higher are truly great teams that really dominated their opponents. (A negative Power Index means a team is below average.)

The teams selected are the 12 highest in Power Index since 1950, all of the teams at +6.00 or higher, among teams that won the Super Bowl/NFL title and weren't wild cards. That's how the teams were picked, but that's not necessarily how I picked the winner.

Eddie Epstein works as a consultant to major league baseball teams. He is the co-author, along with ESPN.com's Rob Neyer, of "Baseball Dynasties: The Greatest Teams of All Time." He has been a regular contributor to ESPN.com's baseball coverage and is a huge football fan.