Posted by Neil Paine on January 22, 2010
At the Hall of Fame's website, I came across a post that reminded me of a little research project I had wanted to do but never got around to it... As you probably already know by now, the #1 seeds from each conference have not faced each other in the Super Bowl since 1993, when the Cowboys beat the Bills in SB XXVIII, and in the 19 full playoffs since 1990 (when the league expanded the playoffs to the current 12-team format), the 1-vs-1 matchup has only taken place twice -- 1991 & 1993. Much has been made about this phenomenon, almost to the point that certain people said it was actually a bad thing to be a #1 seed (that HoF page said "there was a slim chance of the Colts and Saints meeting in South Florida in February"), so I wondered, is there something about the current format that discourages #1 seeds from facing off in the Big Game (i.e., what we're seeing since 1990 is to be expected), or are we in the midst of a random stretch where the #1 seeds simply haven't happened to make it very often, and a correction is to be expected in the future?
To find an answer, I did what I usually do in situations like these: I built a Monte Carlo simulation. This time, I simmed the 2009 NFL schedule after assigning a random SRS-style strength rating to each team (just like Doug did here), and used the following equation to find the probability of the home team winning a game:
Home team prob. of winning =~ 1 / (1 + e^(-.438 - .0826*diff))
Where "diff" is the home team's true strength minus the visiting team's true strength. I ran through every game in the season, all the way through the Super Bowl (tracking how often the game featured two #1 seeds), in 19-year blocks, and repeated this process 2,500 times. Here's the distribution that resulted:
|1-vs-1 in 19 Yrs||Count||Pct|
Overall, in the 47,500 simulated seasons, #1 took on #1 in the Super Bowl on 9,472 occasions, or 19.9% of the time. Compare that to the 10.5% observed rate we're looking at since 1990 and there's definitely been a drought in the real-life results -- but how improbable is the current 2-for-19 stretch? Well, in the 2,500 19-year blocks I simulated, a 2-for-19 run happened 397 times, or in 15.9% of the trials, making it the 4th-most-likely outcome behind 3-for-19, 4-for-19, and 5-for-19.
So the answer to the original question is that while what we're seeing now (at least before this weekend's games) is somewhat unlikely, it's certainly not as rare as some of the media coverage would have you believe. If these simulation results hold water, we should see an uptick in the rate of 1-vs-1 matchups at some point, but the simple truth is that the best team in a conference doesn't always make it to the Super Bowl, and the #1 seed isn't always the best team in the conference anyway. Besides, if one of the selling points of the NFL is its parity, is it even such a bad thing that the clear-cut most dominant teams in their respective conferences can only be expected to square off in the Super Bowl 20% of the time?