In order to sort out the performances on a rational basis, for the last couple years I've borrowed the RPI system of ranking the NCAA basketball teams, based on their own wins, the wins of their opponents, and the wins of their opponents' opponents. The results are weighted and combined, and yield a blend of schedule strength and positive outcomes (ie, victories) to separate the lions of the gridiron from, well, the gridiron Lions.

Here's how it breaks down: each team plays 16 games and collects anywhere from zero to 16 wins. That win total translates to a percentage of the possible wins, which we all recognize as "winning percentage." St. Louis took the win pct crown this year at .875, followed by the Steelers and Bears at .813. Because this is the only set of outcomes that the teams are able to control themselves (ie, it's within their power to increase their win total if they play better), this percentage should be heavily weighted in the power ratings. After all, the idea is to win your games, right?

But 16 games isn't much of a sample, and you can't really say too much about the difference between the Rams' 14-2, and say, the Packers' 12-4. Is 125 percentage points a big gap? It's hard to rely on that number by itself, but any discussion of power starts with your ability to win, so we assign a weight of 40% to the base win percentage.

Still, we need to go deeper and see how their opponents fared in their own games, to see whether one team played a relatively tougher slate of games, against better opponents. So for each team, we compile the win total of all 16 teams played during the season, to come up with an opponents' win total, out of a possible 256 (16 opponents times 16 games). To continue with the example, the Rams' opponents won 121 games between them, for a .473 average. The Steelers' opponents won only 107 games. So not only did the Rams win more games, they won them against what appears to be tougher competition.

However, these numbers can be greatly skewed by the presence of very good or very bad teams within one's own division. The Rams benefitted from two games against the Carolina Panthers, who added just two wins to St. Louis' opponent wins total. The Steelers, on the other hand, played all its division games against opponents with at least 6 wins. (Interestingly, despite this the Rams have the higher opponent win pct. This is in part by design, since the Rams played a 2nd place schedule this year; the Steelers a 4th place schedule.) These numbers, while less volatile in their range than basic win totals, are still subject to small sample sizes (only 256 games), and a team cannot control who they play, and how those teams fare. So we assign a weight of only 20% to this percentage.

Finally, we go even deeper into the numbers, and record the winning percentage of the opponents of the opponents played in a season. This yields a sample of 4096 games for each team, which is plenty to minimize statistical error. These numbers are also out of a team's control, but because there are so many games to review, any differences between teams are likely to be significant. Thus, we will weight these final figures 40% as well.

So the only thing left to do is to take the total wins, wins of their opponents, and wins of _their_ opponents, weight them (multplying them by either .4 or .2), and divide that number by the number of total wins that would equal a perfectly average, .500 season. An 8-8 season is .500, so average is eight. Half of 256 wins (16*16) is 128 wins, and half of 4096 is 2048. 8+128+2048 is 2184 wins, which becomes 848 after weighting. We divide the weighted total of wins by 848, and then multiply that total by 1000. What you end up with is the power rating you see in the table. The perfectly average score would be 1000, so the higher you are above 1000, the better.

Looking at the results, we see that, despite having an easy schedule on the surface (against teams compiling a .418 winning percentage), the Steelers end up on top, with a power rating of 1049. How do they manage it? By winning most of their games as they should, obviously---but also because the teams they played apparently had weak records because they played tough teams. In fact, Pittsburgh's opponents had the toughest cumulative schedule of any team.

Note that eight of the top 12 teams are among the 12 teams in the playoffs, but not necessarily in seeded order. The Steelers are rightfully at the top, but the Rams are down at #4. The Packers show up at #2, while the Bears--who won the division over the Pack--are at #7. The four playoff teams not in the top 12? The New York Jets (seeded #6, ranked #13), Tampa Buccaneers (seeded #6, ranked #16), Oakland Raiders (seeded #3, ranked #20), and Philadelphia Eagles--seeded #3 in the NFC, but ranked at a dismal #27--barely above the Washington Redskins, who won three fewer games.

If we were to predict the NCAA-like "Final Four" from these rankings, we should expect to see a Rams-Packers/Steelers-Patriots matchup. Unfortunately the Eagles' win over Tampa means that Green Bay would meet the Rams in the Divisional Championships first, but the Steelers and Patriots could well meet for the AFC Championship.

Enjoy reading over the results!

:: comments to mark bunster