Even the 'best-ever' teams have no title guarantees

For most of the season, NFL fans have been asking the question, "Are the New England Patriots the greatest team in NFL history?"

This week, the question everyone is asking has changed. Now everyone wants to know whether Sunday's near-loss to the Philadelphia Eagles "proves the Patriots are beatable."

All this shock over the Patriots' needing a come-from-behind victory seems a little silly once you look back at NFL history. The great teams of the past all had one or two games similar to last weekend's Patriots-Eagles game, games in which they fell behind an inferior opponent and narrowly escaped with a victory. No team is going to engineer 19 straight blowouts.

Of course the Patriots are beatable. Every team in NFL history has been beatable. Even the 1972 Miami Dolphins were beatable; it just so happens that no opponent actually managed it over the span of a year. The next season, the Dolphins came back with pretty much the same roster and won the Super Bowl again, but they also lost twice during the 1973 regular season. Every team is beatable.

Just a few examples:

  • The perfect 1972 Dolphins nearly blew a home game to the 4-9-1 Buffalo Bills, winning by a single point.

  • Despite the friendly tundra of Lambeau Field, the 1962 Packers had to stop the 7-7 Baltimore Colts at the goal line three times to escape with a four-point victory.

  • The 1985 Bears were trailing at halftime in both their games against the pathetic 2-14 Tampa Bay Buccaneers. They won those games by a combined total of just 18 points. They also were losing to the 8-8 Green Bay Packers in the middle of the fourth quarter but pulled out a 16-10 win.

    The Patriots still are on track to put up the greatest regular season in modern NFL history. In fact, this might count as the greatest regular season in modern NFL history even if the Pats incur a narrow loss at the hands of the Steelers or Giants.

    In 2002, sportswriter and statistician Eddie Epstein wrote a book called "Dominance: The Best Seasons of Pro Football's Greatest Teams." Epstein chose which teams to write about using a stat he called "Adjusted Power Index." Through 11 weeks of 2007, the Patriots have the greatest API in NFL history.

    API measures the number of standard deviations away from the league average for four stats -- points scored, points allowed, yards gained and yards allowed -- then adjusts for strength of schedule. It sounds nerdy, but the basic idea is to reward teams that not only dominate the league but dominate in a year when lots of teams are close to average, rather than in a year when a few good teams beat up on a few bad teams.

    Only 21 teams since 1950 had API ratings above 6.00, and 13 of those teams eventually won the Super Bowl (or, before 1966, the NFL Championship). Believe it or not, the team with the highest API ever before this year was not one among the champions. Before 2007, the highest API belonged to the 2001 St. Louis Rams, the team whose upset loss in Super Bowl XXXVI launched the Patriots' dynasty.

    The Best Ever?

    Here are the best API ratings since 1950, along with the rating of the current Patriots team through 11 games.

    The Rams actually have a higher "Power Index" than the Patriots before strength of schedule is applied, but the Pats have played an above-average schedule this season. Not counting games against New England, the Patriots' past opponents are a combined 58-52. Their strength of schedule changes in the final five weeks, thanks to games against the Jets and Dolphins, so for the Patriots to finish the season with a higher API than the 2001 Rams, they actually will need to play better than they have so far this season.

    (By the way, New England isn't the only team over the magic 6.00 barrier this season. Indianapolis has an API of 6.17 through 11 games.)

    Does this mean the Patriots are definitely the best team of all time? Well, there's more to judging teams than a single statistic such as API. Conveniently, "Dominance" got its start as a series of columns on ESPN.com in spring 2001. You can go back and read what Epstein had to say about the top dozen teams in NFL history, and you can see which team he picked as the greatest.

    Epstein didn't pick the 1996 Packers as the best team ever, even though they had the highest API of any Super Bowl champion. He didn't pick the 1972 Dolphins as the best team ever, even though they went undefeated. Epstein picked the 1985 Bears as the best team ever, largely because they were even more dominant in the postseason than in the regular season.

    We can't really compare the 2007 Patriots to that Bears team until we see what the Patriots do come playoff time. Right now, the Pats sure look like the greatest team in NFL history. Nonetheless, no matter how good they are in the regular season -- even if they finish 16-0 -- a Super Bowl title is not inevitable.

    Just ask the team with the most dominant regular season in NFL history: the non-champion 2001 Rams. Some people thought that team was unbeatable, but they were proved wrong --by Bill Belichick, Tom Brady and the New England Patriots.

    Aaron Schatz is president of Football Outsiders Inc. and the lead author of Pro Football Prospectus 2007 and 2008.